Problem: Theseus has just arrived to Crete to fight Minotaur. He found a labyrinth that has a form of a rectangular field of size n × m and consists of blocks of size 1 × 1.

Each block of the labyrinth has a button that rotates all blocks 90 degrees clockwise. Each block rotates around its center and doesn't change its position in the labyrinth. Also, each block has some number of doors (possibly none). In one minute, Theseus can either push the button in order to rotate all the blocks 90 degrees clockwise or pass to the neighbouring block. Theseus can go from block A to some neighbouring block B only if block A has a door that leads to block B and block B has a door that leads to block A.

Theseus found an entrance to labyrinth and is now located in block (xT, yT) — the block in the row xT and column yT. Theseus know that the Minotaur is hiding in block (xM, yM) and wants to know the minimum number of minutes required to get there.

Theseus is a hero, not a programmer, so he asks you to help him.

Input

The first line of the input contains two integers n and m (1 ≤ n, m ≤ 1000) — the number of rows and the number of columns in labyrinth, respectively.

Each of the following n lines contains m characters, describing the blocks of the labyrinth. The possible characters are:

  * «+» means this block has 4 doors (one door to each neighbouring block); 
  * «-» means this block has 2 doors — to the left and to the right neighbours; 
  * «|» means this block has 2 doors — to the top and to the bottom neighbours; 
  * «^» means this block has 1 door — to the top neighbour; 
  * «>» means this block has 1 door — to the right neighbour; 
  * «<» means this block has 1 door — to the left neighbour; 
  * «v» means this block has 1 door — to the bottom neighbour;
  * «L» means this block has 3 doors — to all neighbours except left one; 
  * «R» means this block has 3 doors — to all neighbours except right one; 
  * «U» means this block has 3 doors — to all neighbours except top one; 
  * «D» means this block has 3 doors — to all neighbours except bottom one;
  * «*» means this block is a wall and has no doors. 



Left, right, top and bottom are defined from representing labyrinth as a table, where rows are numbered from 1 to n from top to bottom and columns are numbered from 1 to m from left to right.

Next line contains two integers — coordinates of the block (xT, yT) (1 ≤ xT ≤ n, 1 ≤ yT ≤ m), where Theseus is initially located.

Last line contains two integers — coordinates of the block (xM, yM) (1 ≤ xM ≤ n, 1 ≤ yM ≤ m), where Minotaur hides.

It's guaranteed that both the block where Theseus starts and the block where Minotaur is hiding have at least one door. Theseus and Minotaur may be initially located at the same block.

Output

If Theseus is not able to get to Minotaur, then print -1 in the only line of the output. Otherwise, print the minimum number of minutes required to get to the block where Minotaur is hiding.

Examples

Input

2 2
+*
*U
1 1
2 2


Output

-1

Input

2 3
&lt;&gt;&lt;
&gt;&lt;&gt;
1 1
2 1


Output

4

Note

Assume that Theseus starts at the block (xT, yT) at the moment 0.

Solution (in JAVA):

Solution:
import java.awt.*;
import java.io.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.*;
import java.util.List;
import java.util.Queue;

import static java.lang.Math.max;
import static java.lang.Math.min;


public class D implements Runnable{

    // SOLUTION AT THE TOP OF CODE!!!
    // HACK ME PLEASE IF YOU CAN!!!
    // PLEASE!!!
    // PLEASE!!!
    // PLEASE!!!

    private final static boolean FIRST_INPUT_STRING = false;
    private final static boolean MULTIPLE_TESTS = true;
    private final boolean ONLINE_JUDGE = !new File("input.txt").exists();
//    private final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;

    private final static int MAX_STACK_SIZE = 128;

    private final static boolean OPTIMIZE_READ_NUMBERS = false;

    /////////////////////////////////////////////////////////////////////

    private final static Random rnd = new Random();
    private final static String fileName = "";
    
    private final static long MODULO = 1000 * 1000 * 1000 + 7;

    int rotate(int mask, int times) {
        mask <<= times;
        int small = mask & 0b1111;
        int large = mask >> 4;
        return small | large;
    }

    // THERE SOLUTION STARTS!!!
    private void solve() {
        final String types = "" +
                "+-|" +
                "^><v" +
                "LRUD" +
                "*";
        final int[] masks = {
            0b1111, 0b0101, 0b1010,
            0b1000, 0b0001, 0b0100, 0b0010,
            0b1011, 0b1110, 0b0111, 0b1101,
            0b0000
        };

        final int RIGHT = 0, DOWN = 1, LEFT = 2, UP = 3;

        int n = readInt();
        int m = readInt();
        char[][] field = readCharField(n);

        int xStart = readInt() - 1, yStart = readInt() - 1;
        int xEnd = readInt() - 1, yEnd = readInt() - 1;

        int[][][] distances = new int[4][n][m];
        for (int[][] d2 : distances) {
            for (int[] d1 : d2) Arrays.fill(d1, -1);
        }

        class Triple {
            int x, y, times;

            public Triple(int x, int y, int times) {
                this.x = x;
                this.y = y;
                this.times = times;
            }
        }

        Queue<Triple> queue = new ArrayDeque<>();
        queue.add(new Triple(xStart, yStart, 0));
        distances[0][xStart][yStart] = 0;

        while (queue.size() > 0) {
            Triple from = queue.poll();
            int fromDistance = distances[from.times][from.x][from.y];

            int next = (from.times + 1) % 4;
            if (distances[next][from.x][from.y] == -1) {
                distances[next][from.x][from.y] = fromDistance + 1;
                queue.add(new Triple(from.x, from.y, next));
            }

            int fromIndex = types.indexOf(field[from.x][from.y]);
            int fromMask = rotate(masks[fromIndex], from.times);

            for (int[] step : steps) {
                int toX = from.x + step[0], toY = from.y + step[1];
                if (!checkCell(toX, n, toY, m)) continue;
                if (distances[from.times][toX][toY] != -1) continue;

                int toIndex = types.indexOf(field[toX][toY]);
                int toMask = rotate(masks[toIndex], from.times);

                boolean can = false;
                if (from.y < toY) {
                    can = checkBit(fromMask, RIGHT) && checkBit(toMask, LEFT);
                } else if (from.y > toY) {
                    can = checkBit(fromMask, LEFT) && checkBit(toMask, RIGHT);
                } else if (from.x < toX) {
                    can = checkBit(fromMask, DOWN) && checkBit(toMask, UP);
                } else if (from.x > toX) {
                    can = checkBit(fromMask, UP) && checkBit(toMask, DOWN);
                }

                if (can) {
                    distances[from.times][toX][toY] = fromDistance + 1;
                    queue.add(new Triple(toX, toY, from.times));
                }
            }
        }

        int answer = -1;
        for (int time = 0; time < 4; ++time) {
            if (distances[time][xEnd][yEnd] == -1) continue;

            if (answer == -1 || answer > distances[time][xEnd][yEnd]) {
                answer = distances[time][xEnd][yEnd];
            }
        }

        out.println(answer);
    }

    /////////////////////////////////////////////////////////////////////

    private static long add(long a, long b) { return (a + b) % MODULO; }
    private static long subtract(long a, long b) { return add(a, MODULO - b % MODULO); }
    private static long mult(long a, long b) { return (a * b) % MODULO; }

    /////////////////////////////////////////////////////////////////////

    public void run(){
        try{
            timeInit();
            Locale.setDefault(Locale.US);

            init();

            if (ONLINE_JUDGE) {
                solve();
            } else {
                do {
                    try {
                        timeInit();
                        solve();
                        time();

                        out.println();
                        out.flush();
                    } catch (NumberFormatException e) {
                        break;
                    } catch (NullPointerException e) {
                        if (FIRST_INPUT_STRING) break;
                        else throw e;
                    }
                } while (MULTIPLE_TESTS);
            }

            out.close();
            time();
        }catch (Exception e){
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }

    /////////////////////////////////////////////////////////////////////

    private BufferedReader in;
    private OutputWriter out;
    private StringTokenizer tok = new StringTokenizer("");

    public static void main(String[] args){
        new Thread(null, new D(), "", MAX_STACK_SIZE * (1L << 20)).start();
    }

    /////////////////////////////////////////////////////////////////////

    private void init() throws FileNotFoundException{
        Locale.setDefault(Locale.US);

        if (ONLINE_JUDGE){
            if (fileName.isEmpty()) {
                in = new BufferedReader(new InputStreamReader(System.in));
                out = new OutputWriter(System.out);
            } else {
                in = new BufferedReader(new FileReader(fileName + ".in"));
                out = new OutputWriter(fileName + ".out");
            }
        }else{
            in = new BufferedReader(new FileReader("input.txt"));
            out = new OutputWriter("output.txt");
        }
    }

    ////////////////////////////////////////////////////////////////

    private long timeBegin;

    private void timeInit() {
        this.timeBegin = System.currentTimeMillis();
    }

    private void time(){
        long timeEnd = System.currentTimeMillis();
        System.err.println("Time = " + (timeEnd - timeBegin));
    }

    private void debug(Object... objects){
        if (ONLINE_JUDGE){
            for (Object o: objects){
                System.err.println(o.toString());
            }
        }
    }

    /////////////////////////////////////////////////////////////////////

    private String delim = " ";

    private String readLine() {
        try {
            return in.readLine();
        } catch (IOException e) {
            throw new RuntimeIOException(e);
        }
    }

    private String readString() {
        try {
            while(!tok.hasMoreTokens()){
                tok = new StringTokenizer(readLine(), delim);
            }

            return tok.nextToken(delim);
        } catch (NullPointerException e) {
            return null;
        }
    }

    /////////////////////////////////////////////////////////////////

    private final char NOT_A_SYMBOL = '\0';

    private char readChar() {
        try {
            int intValue = in.read();

            if (intValue == -1){
                return NOT_A_SYMBOL;
            }

            return (char) intValue;
        } catch (IOException e) {
            throw new RuntimeIOException(e);
        }
    }

    private char[] readCharArray() {
        return readLine().toCharArray();
    }

    private char[][] readCharField(int rowsCount) {
        char[][] field = new char[rowsCount][];
        for (int row = 0; row < rowsCount; ++row) {
            field[row] = readCharArray();
        }

        return field;
    }

    /////////////////////////////////////////////////////////////////

    private long optimizedReadLong() {
        int sign = 1;
        long result = 0;
        boolean started = false;
        while (true) {
            try {
                int j = in.read();
                if (-1 == j) {
                    if (started) return sign * result;
                    throw new NumberFormatException();
                }

                if (j == '-') {
                    if (started) throw new NumberFormatException();
                    sign = -sign;
                }

                if ('0' <= j && j <= '9') {
                    result = result * 10 + j - '0';
                    started = true;
                } else if (started) {
                    return sign * result;
                }
            } catch (IOException e) {
                throw new RuntimeIOException(e);
            }
        }
    }

    private int readInt() {

        if (!OPTIMIZE_READ_NUMBERS) {
            return Integer.parseInt(readString());
        } else {
            return (int) optimizedReadLong();
        }
    }

    private int[] readIntArray(int size) {
        int[] array = new int[size];

        for (int index = 0; index < size; ++index){
            array[index] = readInt();
        }

        return array;
    }

    private int[] readSortedIntArray(int size) {
        Integer[] array = new Integer[size];

        for (int index = 0; index < size; ++index) {
            array[index] = readInt();
        }
        Arrays.sort(array);

        int[] sortedArray = new int[size];
        for (int index = 0; index < size; ++index) {
            sortedArray[index] = array[index];
        }

        return sortedArray;
    }

    private int[] readIntArrayWithDecrease(int size) {
        int[] array = readIntArray(size);

        for (int i = 0; i < size; ++i) {
            array[i]--;
        }

        return array;
    }

    ///////////////////////////////////////////////////////////////////

    private int[][] readIntMatrix(int rowsCount, int columnsCount) {
        int[][] matrix = new int[rowsCount][];

        for (int rowIndex = 0; rowIndex < rowsCount; ++rowIndex) {
            matrix[rowIndex] = readIntArray(columnsCount);
        }

        return matrix;
    }

    private int[][] readIntMatrixWithDecrease(int rowsCount, int columnsCount) {
        int[][] matrix = new int[rowsCount][];

        for (int rowIndex = 0; rowIndex < rowsCount; ++rowIndex) {
            matrix[rowIndex] = readIntArrayWithDecrease(columnsCount);
        }

        return matrix;
    }

    ///////////////////////////////////////////////////////////////////

    private long readLong() {
        if (!OPTIMIZE_READ_NUMBERS) {
            return Long.parseLong(readString());
        } else {
            return optimizedReadLong();
        }
    }

    private long[] readLongArray(int size) {
        long[] array = new long[size];

        for (int index = 0; index < size; ++index){
            array[index] = readLong();
        }

        return array;
    }

    ////////////////////////////////////////////////////////////////////

    private double readDouble() {
        return Double.parseDouble(readString());
    }

    private double[] readDoubleArray(int size) {
        double[] array = new double[size];

        for (int index = 0; index < size; ++index){
            array[index] = readDouble();
        }

        return array;
    }

    ////////////////////////////////////////////////////////////////////

    private BigInteger readBigInteger() {
        return new BigInteger(readString());
    }

    private BigDecimal readBigDecimal() {
        return new BigDecimal(readString());
    }

    /////////////////////////////////////////////////////////////////////

    private Point readPoint() {
        int x = readInt();
        int y = readInt();
        return new Point(x, y);
    }

    private Point[] readPointArray(int size) {
        Point[] array = new Point[size];

        for (int index = 0; index < size; ++index){
            array[index] = readPoint();
        }

        return array;
    }

    /////////////////////////////////////////////////////////////////////

    @Deprecated
    private List<Integer>[] readGraph(int vertexNumber, int edgeNumber) {
        @SuppressWarnings("unchecked")
        List<Integer>[] graph = new List[vertexNumber];

        for (int index = 0; index < vertexNumber; ++index){
            graph[index] = new ArrayList<Integer>();
        }

        while (edgeNumber-- > 0){
            int from = readInt() - 1;
            int to = readInt() - 1;

            graph[from].add(to);
            graph[to].add(from);
        }

        return graph;
    }

    private static class GraphBuilder {

        final int size;
        final List<Integer>[] edges;

        static GraphBuilder createInstance(int size) {
            List<Integer>[] edges = new List[size];
            for (int v = 0; v < size; ++v) {
                edges[v] = new ArrayList<Integer>();
            }

            return new GraphBuilder(edges);
        }

        private GraphBuilder(List<Integer>[] edges) {
            this.size = edges.length;
            this.edges = edges;
        }

        public void addEdge(int from, int to) {
            addDirectedEdge(from, to);
            addDirectedEdge(to, from);
        }

        public void addDirectedEdge(int from, int to) {
            edges[from].add(to);
        }

        public int[][] build() {
            int[][] graph = new int[size][];
            for (int v = 0; v < size; ++v) {
                List<Integer> vEdges = edges[v];
                graph[v] = castInt(vEdges);
            }

            return graph;
        }
    }

    private final static int ZERO_INDEXATION = 0, ONE_INDEXATION = 1;

    private int[][] readUnweightedGraph(int vertexNumber, int edgesNumber) {
        return readUnweightedGraph(vertexNumber, edgesNumber, ONE_INDEXATION, false);
    }

    private int[][] readUnweightedGraph(int vertexNumber, int edgesNumber,
                                        int indexation, boolean directed
    ) {
        GraphBuilder graphBuilder = GraphBuilder.createInstance(vertexNumber);
        for (int i = 0; i < edgesNumber; ++i) {
            int from = readInt() - indexation;
            int to = readInt() - indexation;

            if (directed) graphBuilder.addDirectedEdge(from, to);
            else graphBuilder.addEdge(from, to);
        }

        return graphBuilder.build();
    }

    private static class Edge {
        int to;
        int w;

        Edge(int to, int w) {
            this.to = to;
            this.w = w;
        }
    }

    private Edge[][] readWeightedGraph(int vertexNumber, int edgesNumber) {
        return readWeightedGraph(vertexNumber, edgesNumber, ONE_INDEXATION, false);
    }

    private Edge[][] readWeightedGraph(int vertexNumber, int edgesNumber,
                                       int indexation, boolean directed) {
        @SuppressWarnings("unchecked")
        List<Edge>[] graph = new List[vertexNumber];
        for (int v = 0; v < vertexNumber; ++v) {
            graph[v] = new ArrayList<Edge>();
        }

        while (edgesNumber --> 0) {
            int from = readInt() - indexation;
            int to = readInt() - indexation;
            int w = readInt();

            graph[from].add(new Edge(to, w));
            if (!directed) graph[to].add(new Edge(from, w));
        }

        Edge[][] graphArrays = new Edge[vertexNumber][];
        for (int v = 0; v < vertexNumber; ++v) {
            graphArrays[v] = graph[v].toArray(new Edge[0]);
        }

        return graphArrays;
    }

    /////////////////////////////////////////////////////////////////////

    private static class IntIndexPair {

        static Comparator<IntIndexPair> increaseComparator = new Comparator<D.IntIndexPair>() {

            @Override
            public int compare(D.IntIndexPair indexPair1, D.IntIndexPair indexPair2) {
                int value1 = indexPair1.value;
                int value2 = indexPair2.value;

                if (value1 != value2) return value1 - value2;

                int index1 = indexPair1.index;
                int index2 = indexPair2.index;

                return index1 - index2;
            }
        };

        static Comparator<IntIndexPair> decreaseComparator = new Comparator<D.IntIndexPair>() {

            @Override
            public int compare(D.IntIndexPair indexPair1, D.IntIndexPair indexPair2) {
                int value1 = indexPair1.value;
                int value2 = indexPair2.value;

                if (value1 != value2) return -(value1 - value2);

                int index1 = indexPair1.index;
                int index2 = indexPair2.index;

                return index1 - index2;
            }
        };

        static IntIndexPair[] from(int[] array) {
            IntIndexPair[] iip = new IntIndexPair[array.length];
            for (int i = 0; i < array.length; ++i) {
                iip[i] = new IntIndexPair(array[i], i);
            }

            return iip;
        }

        int value, index;

        IntIndexPair(int value, int index) {
            super();
            this.value = value;
            this.index = index;
        }

        int getRealIndex() {
            return index + 1;
        }
    }

    private IntIndexPair[] readIntIndexArray(int size) {
        IntIndexPair[] array = new IntIndexPair[size];

        for (int index = 0; index < size; ++index) {
            array[index] = new IntIndexPair(readInt(), index);
        }

        return array;
    }

    /////////////////////////////////////////////////////////////////////

    private static class OutputWriter extends PrintWriter {

        final int DEFAULT_PRECISION = 12;

        private int precision;
        private String format, formatWithSpace;

        {
            precision = DEFAULT_PRECISION;

            format = createFormat(precision);
            formatWithSpace = format + " ";
        }

        OutputWriter(OutputStream out) {
            super(out);
        }

        OutputWriter(String fileName) throws FileNotFoundException {
            super(fileName);
        }

        int getPrecision() {
            return precision;
        }

        void setPrecision(int precision) {
            precision = max(0, precision);
            this.precision = precision;

            format = createFormat(precision);
            formatWithSpace = format + " ";
        }

        String createFormat(int precision){
            return "%." + precision + "f";
        }

        @Override
        public void print(double d){
            printf(format, d);
        }
        
        @Override
        public void println(double d){
            print(d);
            println();
        }

        void printWithSpace(double d){
            printf(formatWithSpace, d);
        }

        void printAll(double...d){
            for (int i = 0; i < d.length - 1; ++i){
                printWithSpace(d[i]);
            }

            print(d[d.length - 1]);
        }

        void printlnAll(double... d){
            printAll(d);
            println();
        }
        
        void printAll(int... array) {
        	for (int value : array) {
        		print(value + " ");
        	}
        }
        
        void printlnAll(int... array) {
        	printAll(array);
        	println();
        }
        
        void printAll(long... array) {
        	for (long value : array) {
        		print(value + " ");
        	}
        }
        
        void printlnAll(long... array) {
        	printAll(array);
        	println();
        }
    }

    /////////////////////////////////////////////////////////////////////

    private static class RuntimeIOException extends RuntimeException {

        /**
         *
         */
        private static final long serialVersionUID = -6463830523020118289L;

        RuntimeIOException(Throwable cause) {
            super(cause);
        }
    }

    /////////////////////////////////////////////////////////////////////
    //////////////// Some useful constants andTo functions ////////////////
    /////////////////////////////////////////////////////////////////////

    private static final int[][] steps = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}};
    private static final int[][] steps8 = {
            {-1, 0}, {1, 0}, {0, -1}, {0, 1},
            {-1, -1}, {1, 1}, {1, -1}, {-1, 1}
    };

    private static boolean checkCell(int row, int rowsCount, int column, int columnsCount) {
        return checkIndex(row, rowsCount) && checkIndex(column, columnsCount);
    }

    private static boolean checkIndex(int index, int lim){
        return (0 <= index && index < lim);
    }

    /////////////////////////////////////////////////////////////////////

    private static int getBit(long mask, int bit) { return (int)((mask >> bit) & 1); }
    private static boolean checkBit(long mask, int bit){
        return getBit(mask, bit) != 0;
    }

    /////////////////////////////////////////////////////////////////////

    private static long getSum(int[] array) {
        long sum = 0;
        for (int value: array) {
            sum += value;
        }

        return sum;
    }

    private static Point getMinMax(int[] array) {
        int min = array[0];
        int max = array[0];

        for (int index = 0, size = array.length; index < size; ++index, ++index) {
            int value = array[index];

            if (index == size - 1) {
                min = min(min, value);
                max = max(max, value);
            } else {
                int otherValue = array[index + 1];

                if (value <= otherValue) {
                    min = min(min, value);
                    max = max(max, otherValue);
                } else {
                    min = min(min, otherValue);
                    max = max(max, value);
                }
            }
        }

        return new Point(min, max);
    }

    /////////////////////////////////////////////////////////////////////

    private static boolean isPrime(int x) {
        if (x < 2) return false;
        for (int d = 2; d * d <= x; ++d) {
            if (x % d == 0) return false;
        }

        return true;
    }
    private static int[] getPrimes(int n) {
        boolean[] used = new boolean[n];
        used[0] = used[1] = true;

        int size = 0;
        for (int i = 2; i < n; ++i) {
            if (!used[i]) {
                ++size;
                for (int j = 2 * i; j < n; j += i) {
                    used[j] = true;
                }
            }
        }

        int[] primes = new int[size];
        for (int i = 0, cur = 0; i < n; ++i) {
            if (!used[i]) {
                primes[cur++] = i;
            }
        }

        return primes;
    }

    /////////////////////////////////////////////////////////////////////

    int[] getDivisors(int value) {
        List<Integer> divisors = new ArrayList<Integer>();
        for (int divisor = 1; divisor * divisor <= value; ++divisor) {
            if (value % divisor == 0) {
                divisors.add(divisor);
                if (divisor * divisor != value) {
                    divisors.add(value / divisor);
                }
            }
        }

        return castInt(divisors);
    }

    /////////////////////////////////////////////////////////////////////

    private static long lcm(long a, long b) {
        return a / gcd(a, b) * b;
    }

    private static long gcd(long a, long b) {
        return (a == 0 ? b : gcd(b % a, a));
    }

/////////////////////////////////////////////////////////////////////

    private interface MultiSet<ValueType> {

        int size();

        void inc(ValueType value);
        boolean dec(ValueType value);

        int count(ValueType value);
    }

    private static abstract class MultiSetImpl
            <ValueType, MapType extends Map<ValueType, Integer>>
            implements MultiSet<ValueType> {

        protected final MapType map;
        protected int size;

        protected MultiSetImpl(MapType map) {
            this.map = map;
            this.size = 0;
        }

        public int size() {
            return size;
        }

        public void inc(ValueType value) {
            int count = count(value);
            map.put(value, count + 1);

            ++size;
        }

        public boolean dec(ValueType value) {
            int count = count(value);
            if (count == 0) return false;

            if (count == 1) map.remove(value);
            else map.put(value, count - 1);

            --size;
            return true;
        }

        public int count(ValueType value) {
            Integer count = map.get(value);
            return (count == null ? 0 : count);
        }
    }

    private static class HashMultiSet<ValueType>
            extends MultiSetImpl<ValueType, Map<ValueType, Integer>> {

        public static <ValueType> MultiSet<ValueType> createMultiSet() {
            Map<ValueType, Integer> map = new HashMap<ValueType, Integer>();
            return new HashMultiSet<ValueType>(map);
        }

        HashMultiSet(Map<ValueType, Integer> map) {
            super(map);
        }
    }

    /////////////////////////////////////////////////////////////////////

    private interface SortedMultiSet<ValueType> extends MultiSet<ValueType> {

        ValueType min();
        ValueType max();

        ValueType pollMin();
        ValueType pollMax();

        ValueType lower(ValueType value);
        ValueType floor(ValueType value);

        ValueType ceiling(ValueType value);
        ValueType higher(ValueType value);
    }

    private static abstract class SortedMultiSetImpl<ValueType>
            extends MultiSetImpl<ValueType, NavigableMap<ValueType, Integer>>
            implements SortedMultiSet<ValueType> {

        SortedMultiSetImpl(NavigableMap<ValueType, Integer> map) {
            super(map);
        }

        @Override
        public ValueType min() {
            return (size == 0 ? null : map.firstKey());
        }

        @Override
        public ValueType max() {
            return (size == 0 ? null : map.lastKey());
        }

        @Override
        public ValueType pollMin() {
            ValueType first = min();
            if (first != null) dec(first);
            return first;
        }

        @Override
        public ValueType pollMax() {
            ValueType last = max();
            dec(last);
            return last;
        }

        @Override
        public ValueType lower(ValueType value) {
            return map.lowerKey(value);
        }

        @Override
        public ValueType floor(ValueType value) {
            return map.floorKey(value);
        }

        @Override
        public ValueType ceiling(ValueType value) {
            return map.ceilingKey(value);
        }

        @Override
        public ValueType higher(ValueType value) {
            return map.higherKey(value);
        }
    }

    private static class TreeMultiSet<ValueType>
            extends SortedMultiSetImpl<ValueType> {

        public static <ValueType> SortedMultiSet<ValueType> createMultiSet() {
            NavigableMap<ValueType, Integer> map = new TreeMap<ValueType, Integer>();
            return new TreeMultiSet<ValueType>(map);
        }

        public static <ValueType> SortedMultiSet<ValueType> createMultiSet(Comparator<ValueType> comparator) {
            NavigableMap<ValueType, Integer> map = new TreeMap<ValueType, Integer>(comparator);
            return new TreeMultiSet<ValueType>(map);
        }

        TreeMultiSet(NavigableMap<ValueType, Integer> map) {
            super(map);
        }
    }

    /////////////////////////////////////////////////////////////////////

    private static class IdMap<KeyType> extends HashMap<KeyType, Integer> {

        /**
         *
         */
        private static final long serialVersionUID = -3793737771950984481L;

        public IdMap() {
            super();
        }

        int register(KeyType key) {
            Integer id = super.get(key);
            if (id == null) {
                super.put(key, id = size());
            }

            return id;
        }

        int getId(KeyType key) {
            return get(key);
        }
    }

    /////////////////////////////////////////////////////////////////////

    private static class SortedIdMapper<ValueType extends Comparable<ValueType>> {

        private List<ValueType> values;

        public SortedIdMapper() {
            this.values = new ArrayList<ValueType>();
        }

        void addValue(ValueType value) {
            values.add(value);
        }

        IdMap<ValueType> build() {
            Collections.sort(values);

            IdMap<ValueType> ids = new IdMap<ValueType>();
            List<ValueType> uniqueValues = new ArrayList<ValueType>();

            for (int index = 0; index < values.size(); ++index) {
                ValueType value = values.get(index);
                if (index == 0 || values.get(index - 1).compareTo(value) != 0) {
                    ids.register(value);
                    uniqueValues.add(value);
                }
            }
            
            values = uniqueValues;

            return ids;
        }
    }

    /////////////////////////////////////////////////////////////////////

    private static int[] castInt(List<Integer> list) {
        int[] array = new int[list.size()];
        for (int i = 0; i < array.length; ++i) {
            array[i] = list.get(i);
        }

        return array;
    }

    private static long[] castLong(List<Long> list) {
        long[] array = new long[list.size()];
        for (int i = 0; i < array.length; ++i) {
            array[i] = list.get(i);
        }

        return array;
    }

    /////////////////////////////////////////////////////////////////////

    /**
     * Generates list with keys 0..<n
     * @param n - exclusive limit of sequence
     */
    private static List<Integer> order(int n) {
        List<Integer> sequence = new ArrayList<Integer>();
        for (int i = 0; i < n; ++i) {
            sequence.add(i);
        }

        return sequence;
    }

    /////////////////////////////////////////////////////////////////////

    interface Rmq {
        int getMin(int left, int right);
        int getMinIndex(int left, int right);
    }

    private static class SparseTable implements Rmq {

        private static final int MAX_BIT = 20;

        int n;
        int[] array;

        SparseTable(int[] array) {
            this.n = array.length;
            this.array = array;
        }

        int[] lengthMaxBits;
        int[][] table;

        int getIndexOfLess(int leftIndex, int rightIndex) {
            return (array[leftIndex] <= array[rightIndex])
                    ? leftIndex
                    : rightIndex;
        }

        SparseTable build() {
            this.lengthMaxBits = new int[n + 1];
            lengthMaxBits[0] = 0;
            for (int i = 1; i <= n; ++i) {
                lengthMaxBits[i] = lengthMaxBits[i - 1];
                int length = (1 << lengthMaxBits[i]);
                if (length + length <= i) ++lengthMaxBits[i];
            }

            this.table = new int[MAX_BIT][n];
            table[0] = castInt(order(n));

            for (int bit = 0; bit < MAX_BIT - 1; ++bit) {
                for (int i = 0, j = (1 << bit); j < n; ++i, ++j) {
                    table[bit + 1][i] = getIndexOfLess(
                            table[bit][i], table[bit][j]
                    );
                }
            }

            return this;
        }

        @Override
        public int getMinIndex(int left, int right) {
            int length = (right - left + 1);

            int bit = lengthMaxBits[length];
            int segmentLength = (1 << bit);

            return getIndexOfLess(
                    table[bit][left], table[bit][right - segmentLength + 1]
            );
        }

        @Override
        public int getMin(int left, int right) {
            return array[getMinIndex(left, right)];
        }
    }

    private static Rmq createRmq(int[] array) {
        return new SparseTable(array).build();
    }

    /////////////////////////////////////////////////////////////////////

    interface Lca {
        Lca build(int root);
        int lca(int a, int b);

        int height(int v);
    }

    private static class LcaRmq implements Lca {

        int n;
        int[][] graph;

        LcaRmq(int[][] graph) {
            this.n = graph.length;
            this.graph = graph;
        }

        int time;

        int[] order;
        int[] heights;
        int[] first;

        Rmq rmq;

        @Override
        public LcaRmq build(int root) {
            this.order = new int[n + n];
            this.heights = new int[n];

            this.first = new int[n];
            Arrays.fill(first, -1);

            this.time = 0;
            dfs(root, 0);

            int[] orderedHeights = new int[n + n];
            for (int i = 0; i < order.length; ++i) {
                orderedHeights[i] = heights[order[i]];
            }

            this.rmq = createRmq(orderedHeights);
            return this;
        }

        void dfs(int from, int height) {
            first[from] = time;
            order[time] = from;
            heights[from] = height;
            ++time;

            for (int to : graph[from]) {
                if (first[to] == -1) {
                    dfs(to, height + 1);

                    order[time] = from;
                    ++time;
                }
            }
        }

        @Override
        public int lca(int a, int b) {
            int aFirst = first[a], bFirst = first[b];
            int left = min(aFirst, bFirst), right = max(aFirst, bFirst);

            int orderIndex = rmq.getMinIndex(left, right);
            return order[orderIndex];
        }

        @Override
        public int height(int v) {
            return heights[v];
        }
    }

    private static class LcaBinary implements Lca {

        private static final int MAX_BIT = 20;

        int n;
        int[][] graph;

        int[] h;
        int[][] parents;

        LcaBinary(int[][] graph) {
            this.n = graph.length;
            this.graph = graph;
        }

        @Override
        public Lca build(int root) {
            this.h = new int[n];

            this.parents = new int[MAX_BIT][n];
            Arrays.fill(parents[0], -1);

            Queue<Integer> queue = new ArrayDeque<Integer>();

            queue.add(root);
            add(root, root);

            while (queue.size() > 0) {
                int from = queue.poll();
                for (int to : graph[from]) {
                    if (parents[0][to] == -1) {
                        add(from, to);
                        queue.add(to);
                    }
                }
            }

            return this;
        }

        void add(int parent, int v) {
            h[v] = h[parent] + 1;
            parents[0][v] = parent;
            for (int bit = 0; bit < MAX_BIT - 1; ++bit) {
                parents[bit + 1][v] = parents[bit][parents[bit][v]];
            }
        }

        @Override
        public int lca(int a, int b) {
            if (h[a] < h[b]) {
                int tmp = a;
                a = b;
                b = tmp;
            }

            int delta = h[a] - h[b];
            for (int bit = MAX_BIT - 1; bit >= 0; --bit) {
                if (delta >= (1 << bit)) {
                    delta -= (1 << bit);
                    a = parents[bit][a];
                }
            }

            if (a == b) return a;

            for (int bit = MAX_BIT - 1; bit >= 0; --bit) {
                int nextA = parents[bit][a], nextB = parents[bit][b];
                if (nextA != nextB) {
                    a = nextA;
                    b = nextB;
                }
            }

            return parents[0][a];
        }

        @Override
        public int height(int v) {
            return h[v];
        }
    }

    private static Lca createLca(int[][] graph, int root) {
        return new LcaRmq(graph).build(root);
    }

    /////////////////////////////////////////////////////////////////////

    private static class BiconnectedGraph {

        int n;
        int[][] graph;

        BiconnectedGraph(int[][] graph) {
            this.n = graph.length;
            this.graph = graph;
        }

        int time;
        int[] tin, up;

        boolean[] used;

        BiconnectedGraph build() {
            calculateTimes();
            condensateComponents();

            return this;
        }

        void calculateTimes() {
            this.tin = new int[n];
            this.up = new int[n];

            this.time = 0;

            this.used = new boolean[n];
            timeDfs(0, -1);
        }

        void timeDfs(int from, int parent) {
            used[from] = true;

            up[from] = tin[from] = time;
            ++time;

            for (int to : graph[from]) {
                if (to == parent) continue;

                if (used[to]) {
                    up[from] = min(up[from], tin[to]);
                } else {
                    timeDfs(to, from);
                    up[from] = min(up[from], up[to]);
                }
            }
        }

        int[] components;
        int[][] componentsGraph;

        int component(int v) { return components[v]; }

        int[][] toGraph() {
            return componentsGraph;
        }

        void condensateComponents() {
            this.components = new int[n];
            Arrays.fill(components, -1);

            for (int v = 0; v < n; ++v) {
                if (components[v] == -1) {
                    componentsDfs(v, v);
                }
            }

            GraphBuilder graphBuilder = GraphBuilder.createInstance(n);

            Set<Point> edges = new HashSet<Point>();
            for (int from = 0; from < n; ++from) {
                int fromComponent = components[from];

                for (int to : graph[from]) {
                    int toComponent = components[to];
                    if (fromComponent == toComponent) continue;

                    Point edge = new Point(fromComponent, toComponent);
                    if (edges.add(edge)) graphBuilder.addDirectedEdge(fromComponent, toComponent);
                }
            }

            this.componentsGraph = graphBuilder.build();
        }

        void componentsDfs(int from, int color) {
            components[from] = color;
            for (int to : graph[from]) {
                if (components[to] != -1) continue;

                if (tin[from] >= up[to] && tin[to] >= up[from]) {
                    componentsDfs(to, color);
                }
            }
        }
    }

    /////////////////////////////////////////////////////////////////////

    private static class VertexBiconnectedGraph {

        static class Edge {
            int to;
            int index;

            Edge(int to, int index) {
                this.to = to;
                this.index = index;
            }
        }

        int n, m;
        List<Edge>[] graph;
        List<Edge> edges;

        VertexBiconnectedGraph(int n) {
            this.n = n;
            this.m = 0;

            this.graph = new List[n];
            for (int v = 0; v < n; ++v) {
                graph[v] = new ArrayList<Edge>();
            }

            this.edges = new ArrayList<Edge>();
        }

        void addEdge(int from, int to) {
            Edge fromToEdge = new Edge(to, m);
            Edge toFromEdge = new Edge(from, m + 1);

            edges.add(fromToEdge);
            edges.add(toFromEdge);

            graph[from].add(fromToEdge);
            graph[to].add(toFromEdge);

            m += 2;
        }

        int time;

        boolean[] used;
        int[] tin, up;
        int[] parents;

        boolean[] isArticulation;

        boolean[] findArticulationPoints() {
            this.isArticulation = new boolean[n];

            this.used = new boolean[n];
            this.parents = new int[n];
            Arrays.fill(parents, -1);

            this.tin = new int[n];
            this.up = new int[n];

            this.time = 0;

            for (int v = 0; v < n; ++v) {
                if (!used[v]) {
                    articulationDfs(v, -1);
                }
            }

            return isArticulation;
        }

        void articulationDfs(int from, int parent) {
            used[from] = true;
            parents[from] = parent;

            ++time;
            up[from] = tin[from] = time;

            int childrenCount = 0;

            for (Edge e : graph[from]) {
                int to = e.to;

                if (to == parent) continue;

                if (used[to]) {
                    up[from] = min(up[from], tin[to]);
                } else {
                    ++childrenCount;

                    articulationDfs(to, from);
                    up[from] = min(up[from], up[to]);
                    if (up[to] >= tin[from] && parent != -1) {
                        isArticulation[from] = true;
                    }
                }
            }

            if (parent == -1 && childrenCount > 1) {
                isArticulation[from] = true;
            }
        }

        int[] edgeColors;
        int maxEdgeColor;

        int[] paintEdges() {
            this.edgeColors = new int[m];
            Arrays.fill(edgeColors, -1);

            this.maxEdgeColor = -1;

            this.used = new boolean[n];

            for (int v = 0; v < n; ++v) {
                if (!used[v]) {
                    ++maxEdgeColor;
                    paintDfs(v, maxEdgeColor, -1);
                }
            }

            return edgeColors;
        }

        void paintEdge(int edgeIndex, int color) {
            if (edgeColors[edgeIndex] != -1) return;

            edgeColors[edgeIndex] = edgeColors[edgeIndex ^ 1] = color;
        }

        void paintDfs(int from, int color, int parent) {
            used[from] = true;

            for (Edge e : graph[from]) {
                int to = e.to;
                if (to == parent) continue;

                if (!used[to]) {
                    if (up[to] >= tin[from]) {
                        int newColor = ++maxEdgeColor;
                        paintEdge(e.index, newColor);
                        paintDfs(to, newColor, from);
                    } else {
                        paintEdge(e.index, color);
                        paintDfs(to, color, from);
                    }
                } else if (up[to] <= tin[from]){
                    paintEdge(e.index, color);
                }
            }
        }

        Set<Integer>[] collectVertexEdgeColors() {
            Set<Integer>[] vertexEdgeColors = new Set[n];
            for (int v = 0; v < n; ++v) {
                vertexEdgeColors[v] = new HashSet<Integer>();
                for (Edge e : graph[v]) {
                    vertexEdgeColors[v].add(edgeColors[e.index]);
                }
            }

            return vertexEdgeColors;
        }

        VertexBiconnectedGraph build() {
            findArticulationPoints();
            paintEdges();
            createComponentsGraph();

            return this;
        }

        int[][] componentsGraph;

        void createComponentsGraph() {
            Set<Integer>[] vertexEdgeColors = collectVertexEdgeColors();

            int edgeColorShift = vertexEdgeColors.length;
            int size = vertexEdgeColors.length + maxEdgeColor + 1;

            GraphBuilder graphBuilder = GraphBuilder.createInstance(size);
            for (int v = 0; v < vertexEdgeColors.length; ++v) {
                for (int edgeColor : vertexEdgeColors[v]) {
                    graphBuilder.addEdge(v, edgeColor + edgeColorShift);
                }
            }

            this.componentsGraph = graphBuilder.build();
        }

        int[][] toGraph() {
            return componentsGraph;
        }
    }

    /////////////////////////////////////////////////////////////////////

    private static class DSU {

        int[] sizes;

        int[] ranks;
        int[] parents;

        static DSU createInstance(int size) {
            int[] sizes = new int[size];
            Arrays.fill(sizes, 1);

            return new DSU(sizes);
        }

        DSU(int[] sizes) {
            this.sizes = sizes;

            int size = sizes.length;

            this.ranks = new int[size];
            Arrays.fill(ranks, 1);

            this.parents = castInt(order(size));
        }

        int get(int v) {
            if (v == parents[v]) return v;
            return parents[v] = get(parents[v]);
        }

        boolean union(int a, int b) {
            a = get(a);
            b = get(b);

            if (a == b) return false;

            if (ranks[a] < ranks[b]) {
                int tmp = a;
                a = b;
                b = tmp;
            }

            parents[b] = a;
            sizes[a] += sizes[b];

            if (ranks[a] == ranks[b]) ++ranks[a];

            return true;
        }
    }

    /////////////////////////////////////////////////////////////////////
    
    static abstract class SegmentTree {
    	
    	int size;
    	boolean lazySupported; 
    	
    	boolean[] lazy;
    	long[] values;
    	
    	long[] tree;
    	
    	SegmentTree(int n, boolean lazySupported) {
    		this.size = n;
    		this.lazySupported = lazySupported;
    		
    		int treeSize = size << 2;
    		
    		this.tree = new long[treeSize];
    		
    		if (lazySupported) {
        		this.lazy = new boolean[treeSize];
        		this.values = new long[treeSize];	
    		}
    	}
    	
    	SegmentTree(int[] a, boolean lazySupported) {
    		this(a.length, lazySupported);
    	}
    	
    	abstract void updateValue(int v, int left, int right, long value);
    	
    	void setLazyValue(int v, long value) {
    		throw new UnsupportedOperationException();
    	}
    	
    	void pushVertex(int v, int vLeft, int vRight) {
    		if (lazy[v]) {
    			setLazyValue(vLeft, values[v]);
    			setLazyValue(vRight, values[v]);
    			
    			lazy[v] = false;
    			values[v] = 0;
    		}
    	}
    	
    	abstract void updateVertex(int v, int vLeft, int vRight);
    	
    	int[] a;
    	void buildTree(int[] a) {
    		this.a = a;
    		
    		buildTree(1, 0, size - 1);
    	}
    	
    	void buildTree(int v, int left, int right) {
    		if (left == right) {
    			updateValue(v, left, right, a[left]);
    		} else {
    			int mid = (left + right) >> 1;
    			int vLeft = (v << 1), vRight = (vLeft + 1);
    			
    			buildTree(vLeft, left, mid);
    			buildTree(vRight, mid + 1, right);
    			
    			updateVertex(v, vLeft, vRight);
    		}
    	}
    	
    	long value;
    	
    	int index;
    	void updateIndex(int index, long value) {
    		this.index = index;
    		this.value = value;
    		
    		updateTreeIndex(1, 0, size - 1);
    	}
    	
    	void updateTreeIndex(int v, int left, int right) {
    		if (left == right) {
    			updateValue(v, left, right, value);
    		} else {
    			int mid = (left + right) >> 1;
    			int vLeft = (v << 1), vRight = (vLeft + 1);
    			
    			if (index <= mid) updateTreeIndex(vLeft, left, mid);
    			else updateTreeIndex(vRight, mid + 1, right);
    			
    			updateVertex(v, vLeft, vRight);
    		}
    	}
    	
    	int start, end;
    	void updateSegment(int start, int end, long value) {
    		this.start = start;
    		this.end = end;
    		this.value = value;
    		
    		updateTreeSegment(1, 0, size - 1);
    	}

        void updateTreeSegment(int v, int left, int right) {
            if (start <= left && right <= end) {
                if (lazySupported) {
                    setLazyValue(v, value);
                } else {
                    updateValue(v, left, right, value);
                }
            } else {
                int mid = (left + right) >> 1;
                int vLeft = (v << 1), vRight = (vLeft + 1);

                if (lazySupported) pushVertex(v, vLeft, vRight);

                if (start <= mid) updateTreeSegment(vLeft, left, mid);
                if (mid < end) updateTreeSegment(vRight, mid + 1, right);

                updateVertex(v, vLeft, vRight);
            }
        }

        abstract void initResult(long... initResultValues);

        abstract void accumulateResult(int v, int left, int right);

        void accumulateIndexResult(int v, int left, int right) {
            accumulateResult(v, left, right);
        }

        void getIndex(int index, long... initResultValues) {
            this.index = index;

            initResult(initResultValues);

            getTreeIndex(1, 0, size - 1);
        }

        void getTreeIndex(int v, int left, int right) {
            if (lazySupported) {
                if (left == right) {
                    accumulateIndexResult(v, left, right);
                } else {
                    int mid = (left + right) >> 1;
                    int vLeft = (v << 1), vRight = (vLeft + 1);

                    pushVertex(v, vLeft, vRight);

                    if (index <= mid) getTreeIndex(vLeft, left, mid);
                    else getTreeIndex(vRight, mid + 1, right);

                    updateVertex(v, vLeft, vRight);
                }
            } else {
                while (left <= right) {
                    accumulateIndexResult(v, left, right);

                    if (left == right) break;

                    int mid = (left + right) >> 1;
                    int vLeft = (v << 1), vRight = (vLeft + 1);

                    if (index <= mid) {
                        v = vLeft;
                        right = mid;
                    } else {
                        v = vRight;
                        left = mid + 1;
                    }
                }
            }
        }
    	
    	void getSegment(int start, int end, long... initResultValues) {
    		this.start = start;
    		this.end = end;
    		
    		initResult(initResultValues);
    		
    		getTreeSegment(1, 0, size - 1);
    	}
    	
    	void getTreeSegment(int v, int left, int right) {
    		if (start <= left && right <= end) {
    			accumulateResult(v, left, right);
    		} else {
    			int mid = (left + right) >> 1;
				int vLeft = (v << 1), vRight = (vLeft + 1);
				
				if (lazySupported) pushVertex(v, vLeft, vRight);
				
				if (start <= mid) getTreeSegment(vLeft, left, mid);
				if (mid < end) getTreeSegment(vRight, mid + 1, right);
				
				if (lazySupported) updateVertex(v, vLeft, vRight);
    		}
    	}
    	
    	int[] toArray() {
    		this.a = new int[size];
    		
    		fillTreeArray(1, 0, size - 1);
    		
    		return a;
    	}
    	
    	void fillTreeArray(int v, int left, int right) {
    		if (left == right) {
    			a[left] = (int)(tree[v]);
    		} else {
    			int mid = (left + right) >> 1;
				int vLeft = (v << 1), vRight = (vLeft + 1);
				
				if (lazySupported) pushVertex(v, vLeft, vRight);
				
				fillTreeArray(vLeft, left, mid);
				fillTreeArray(vRight, mid + 1, right);
				
				if (lazySupported) updateVertex(v, vLeft, vRight);
    		}
    	}
    }
    
    /////////////////////////////////////////////////////////////////////

    static class Treap {

        static class Node {

            static int getCount(Node node) {
                return (node == null ? 0 : node.count);
            }

            static long getValue(Node node) {
                return (node == null ? 0 : node.value);
            }

            static long getSum(Node node) {
                return (node == null ? 0 : node.sum);
            }

            long priority;

            Node left, right;
            int count;

            long value, sum;
            boolean reversed;

            Node(long value) {
                this.priority = rnd.nextLong();
                this.count = 1;
                this.value = value;
                this.sum = value;
                this.reversed = false;
            }

            void update() {
                this.count = getCount(left) + getCount(right) + 1;
                this.sum = getSum(left) + getSum(right) + value;
            }

            void push() {
                if (reversed) {
                    Node tmp = left;
                    left = right;
                    right = tmp;

                    if (left != null) left.reversed ^= true;
                    if (right != null) right.reversed ^= true;

                    reversed = false;
                }
            }
        }

        Node root;
        Node[] splitParts;

        Treap() {
            this.root = null;
            this.splitParts = new Node[2];
        }

        void addValue(long value) {
            Node node = new Node(value);
            root = merge(root, node);
        }

        long getSegmentSum(int startInclusive, int endExclusive) {
            splitClear();
            split(root, endExclusive);

            Node leftMid = splitParts[0];
            Node right = splitParts[1];

            splitClear();
            split(leftMid, startInclusive);

            Node left = splitParts[0];
            Node mid = splitParts[1];

            long result = Node.getSum(mid);

            root = merge(left, mid);
            root = merge(root, right);

            return result;
        }

        void updateValue(Node node, int index, long delta) {
            if (node == null) return;

            node.push();

            int leftCount = Node.getCount(node.left);
            if (index < leftCount) updateValue(node.left, index, delta);
            else if (index == leftCount) node.value += delta;
            else updateValue(node.right, index - leftCount - 1, delta);

            node.update();
        }

        long getValueByIndex(Node node, int index) {
            Node result = getNodeByKey(node, index);
            return Node.getValue(result);
        }

        Node getNodeByKey(Node node, int key) {
            if (node == null) return null;

            node.push();

            int leftCount = Node.getCount(node.left);

            Node result;

            if (key < leftCount) result = getNodeByKey(node.left, key);
            else if (key == leftCount) result = node;
            else result = getNodeByKey(node.right, key - leftCount - 1);

            node.update();

            return result;
        }

        Node merge(Node left, Node right) {
            if (left == null) return right;
            if (right == null) return left;

            left.push();
            right.push();

            Node result;

            if (left.priority < right.priority) {
                left.right = merge(left.right, right);
                result = left;
            } else {
                right.left = merge(left, right.left);
                result = right;
            }

            result.update();

            return result;
        }

        void splitClear() {
            splitParts[0] = null;
            splitParts[1] = null;
        }

        void split(Node node, int key) {
            if (node == null) return;

            node.push();

            int leftCount = Node.getCount(node.left);
            if (key < leftCount) {
                split(node.left, key);

                node.left = splitParts[1];
                splitParts[1] = node;

            } else if (key == leftCount) {
                splitParts[0] = node.left;
                splitParts[1] = node;
                node.left = null;
            } else {
                split(node.right, key - leftCount - 1);

                node.right = splitParts[0];
                splitParts[0] = node;
            }

            node.update();
        }
    }

    /////////////////////////////////////////////////////////////////////
}