Problem: You are given a tree that has n vertices, which are numbered from 1 to n, where the vertex number one is the root. Each edge has weight wi and strength pi.

Botanist Innokentiy, who is the only member of the jury of the Olympiad in Informatics, doesn't like broken trees. 

The tree is broken if there is such an edge the strength of which is less than the sum of weight of subtree's edges to which it leads.

It is allowed to reduce weight of any edge by arbitrary integer value, but then the strength of its edge is reduced by the same value. It means if the weight of the edge is 10, and the strength is 12, then by the reducing the weight by 7 its weight will equal 3, and the strength will equal 5. 

It is not allowed to increase the weight of the edge.

Your task is to get the tree, which is not broken, by reducing the weight of edges of the given tree, and also all edged should have the positive weight, moreover, the total weight of all edges should be as large as possible.

It is obvious that the strength of edges can not be negative, however it can equal zero if the weight of the subtree equals zero. 

Input

The first line contains the integer n (1 ≤ n ≤ 2·105) — the number of vertices in the tree. The next n - 1 lines contains the description of edges. Each line contains four integers x, y, w, p (1 ≤ x, y ≤ n, 1 ≤ w ≤ 109, 0 ≤ p ≤ 109), where x and y — vertices which connect the edge (the vertex number x is the parent of the vertex number y), w and p are the weight and the strength of the edge, accordingly. It is guaranteed that the edges describe the tree with the root in the vertex 1.

Output

If it is impossible to get unbroken tree from the given tree, print -1 in the only line.

Otherwise, the output data should contain n lines:

In the first line print the number n — the number of vertices on the tree. 

In the next n - 1 lines print the description of edges of the resulting tree. Each line should contain four integers x, y, w, p (1 ≤ x, y ≤ n, 1 ≤ w ≤ 109, 0 ≤ p ≤ 109), where x and y — vertices, which the edge connects (the vertex number x is the parent of the vertex number y), w and p are the new weight and the strength of the edge, accordingly. 

Print edges in the same order as they are given in input data: the first two integers of each line should not be changed. 

Examples

Input

3
1 3 5 7
3 2 4 3


Output

3
1 3 5 7
3 2 4 3


Input

4
1 3 2 3
3 4 5 1
3 2 3 3


Output

-1

Input

5
1 2 2 4
2 4 1 9
4 5 5 6
4 3 4 8


Output

5
1 2 2 4
2 4 1 9
4 5 1 2
4 3 2 6


Input

7
1 2 5 2
2 3 4 3
1 4 3 7
4 5 4 1
4 6 3 2
6 7 1 6


Output

7
1 2 5 2
2 3 2 1
1 4 3 7
4 5 3 0
4 6 3 2
6 7 1 6

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;

/**
 * @author Ivan Pryvalov (ivan.pryvalov@gmail.com)
 */
public class CF392_Div2_E implements Runnable {

    static EventType eventType = EventType.DEFAULT;
//    static EventType eventType = EventType.GOOGLE_CODE_JAM;

    // Set T=0 if T should be read from input.
    // Set T=1 if there is only one testcase.
    static int T = 1;

    // Set it to `null' when the input is std in.
//    static String inputFilename = null;
//    static String inputFilename = "A-sample.in";
//    static String inputFilename = "A-small-attempt0.in";
    static String inputFilename = null;


    // Set to true if you have prepared a large test with fake data.
    static boolean largeFakeTest = false;
    //Number of tests in the large fake test.
    static int largeFakeTest_T = 1;


    //--------------------------------------------------------------------

    public static class Edge{
        int x, y;
        long w, p;

        boolean visited = false;
        long wChildren = 0;
        long wChildrenReqest = 0;
        long wChildrenMin = 0;
        long wMin;

        int getOtherEndpoint(int u){
            if (x!=u && y!=u)
                throw new RuntimeException();
            return x==u? y : u;
        }
    }

    interface DfsJob{
        void process(Edge parentEdge, Edge edge);
    }


    public static class Solver extends  SolverAbstract{

        int N;
        Edge[] edges;
        List<Edge>[] adj;

        void dfs(int node, Edge parentEdge, DfsJob dfsPreJob, DfsJob dfsPostJob){
            for(Edge edge: adj[node]) if (!edge.visited){
                int childNode = edge.getOtherEndpoint(node);
                if (dfsPreJob!=null)
                    dfsPreJob.process(parentEdge, edge);
                edge.visited = true;
                dfs(childNode, edge, dfsPreJob, dfsPostJob);
                if (dfsPostJob!=null)
                    dfsPostJob.process(parentEdge, edge);
                edge.visited = false;
            }
        }

        @Override
        public void readInput() throws IOException {
            N = scanner.nextInt(); // 2 10^5
            edges = new Edge[N-1];
            adj = new List[N+1];
            for (int i = 1; i <= N; i++) {
                adj[i] = new ArrayList<>();
            }
            for (int i = 0; i < N - 1; i++) {
                Edge edge = new Edge();
                edge.x = scanner.nextInt();
                edge.y = scanner.nextInt();
                edge.w = scanner.nextInt();
                edge.p = scanner.nextInt();
                edges[i] = edge;
                adj[edge.x].add(edge);
                adj[edge.y].add(edge);
            }
            final boolean[] possible = {true};
            dfs(1, null, null, (parentEdge, edge)->{
                if (edge.p < edge.wChildrenMin){
                    possible[0] = false;
                }
                edge.wChildrenReqest = Math.min(edge.p, edge.wChildren);
                edge.wMin = Math.max(1, edge.w - (edge.p - edge.wChildrenMin));
                if (parentEdge!=null){
                    parentEdge.wChildren += edge.wChildrenReqest + edge.w;
                    parentEdge.wChildrenMin += edge.wChildrenMin + edge.wMin;
                }
            });
            if (!possible[0]){
                sb.append("-1").append("\n");
                return;
            }
            dfs(1, null,
                    (parentEdge, edge)->{ // pre
                        if (parentEdge != null){
                            long redChildrenPotential = edge.wChildrenReqest - edge.wChildrenMin;
                            long reduceFromChildren = Math.min(parentEdge.wChildren - parentEdge.wChildrenReqest, redChildrenPotential);
                            edge.wChildrenReqest -= reduceFromChildren;
                            parentEdge.wChildren -= reduceFromChildren;

                            long reduceEdgePotential = edge.w - edge.wMin;
                            long reduceFromEdge = Math.min(parentEdge.wChildren - parentEdge.wChildrenReqest, reduceEdgePotential);
                            edge.w -= reduceFromEdge;
                            edge.p -= reduceFromEdge;
                            parentEdge.wChildren -= reduceFromEdge;
                        }
                    },
                    (parentEdge, edge)->{ // post

                    });
            sb.append(N).append("\n");
            for (int i = 0; i < N - 1; i++) {
                sb.append(edges[i].x).append(" ")
                        .append(edges[i].y).append(" ")
                        .append(edges[i].w).append(" ")
                        .append(edges[i].p).append("\n");
            }
        }

        StringBuilder sb = new StringBuilder();

        @Override
        protected String solve() throws IOException {
            return sb.toString();
        }
    }

    // ------------- Some stardard tools that are currently not tested.

    static class Graph{
        int[][] G;
        int N;

        int[][] A;
        int[][] F;

        int[] path;
        int pathLen;
        boolean[] visited;
        int target;
        boolean flowFound;

        public Graph(int[][] g) {
            G = g;
            N = G.length;
        }

        public int[][] maxflow(int iSource, int iSink) {
            path = new int[N];
            visited = new boolean[N];

            A = new int[N][];
            for (int i = 0; i < N; i++) {
                A[i] = G[i].clone();
            }
            F = new int[N][N];

            target = iSink;
            //dfs from source to sink
            //increase path
            while(true){
                flowFound = false;
                visited[iSource] = true;
                pathLen = 0;
                path[pathLen++] = iSource;
                dfs(iSource);
                if (!flowFound)
                    break;
            }
            return F;
        }

        private void dfs(int u) {
            if (u==target){
                flowFound = true;
                for (int i = 0; i < pathLen-1; i++) {
                    int from = path[i];
                    int to  = path[i+1];
                    F[from][to]++;
                    F[to][from]--;
                }
            }else {
                for (int i = 0; i < N && !flowFound; i++) {
                    if (!visited[i] && A[u][i] > F[u][i]) {
                        visited[i] = true;
                        path[pathLen] = i;
                        pathLen++;
                        dfs(i);
                        visited[i] = false;
                        pathLen--;
                    }
                }
            }
        }
    }

    //--------------------------------------------------------------------

    private void solveAll() throws IOException, InterruptedException {
        long timeStart = System.currentTimeMillis();

        if (T==0) {
            if (largeFakeTest) {
                T = largeFakeTest_T;
            } else {
                T = scanner.nextInt();
            }
        }
        final String[] results = new String[T+1];
        for (int test = 0; test < T; test++) {
            Solver solver = new Solver(){
                @Override
                public void callback() {
                    results[testNo] = answer;
                }
            };
            solver.testNo = test+1;
            if (largeFakeTest) {
                solver.readFakeInput();
            }else{
                solver.readInput();
            }
            solver.solveWrapped();
        }

        long timeEnd = System.currentTimeMillis();
        if (isInputFromFile())
            System.out.println("All tasks are solved! Elapsed time "+(timeEnd-timeStart)/1000.0+" sec.");

        // write all responses in the proper order
        for (int i = 1; i <= T; i++) {
            if (eventType == EventType.GOOGLE_CODE_JAM){
                out.printf("Case #%d: %s", i, results[i]);
            }else {
                out.println(results[i]);
            }
        }
    }

    enum EventType{
        DEFAULT,
        GOOGLE_CODE_JAM
    }

    static boolean isInputFromFile() {
        return inputFilename != null;
    }

    public static abstract class SolverAbstract {
        int testNo;
        String answer = null;

        public void callback(){};

        public abstract void readInput() throws IOException;

        //generate a randomized test with the maximal input values
        public void readFakeInput() throws  IOException{
            throw new RuntimeException("not implemented");
        }

        protected abstract String solve() throws IOException;

        protected void solveWrapped() throws IOException {

            if (isInputFromFile())
                System.out.println("SOLVER: solving task #"+testNo+" out of "+ T+"...");

            answer = solve();
/*
            StringBuilder sbAnswer = new StringBuilder();
            sbAnswer.append(String.format("Case #%d:\n", testNo));
            good.forEach( (k,v) -> {
                sbAnswer.append(k).append(" ");
                for(int x:v){
                    sbAnswer.append(x).append(" ");
                }
                sbAnswer.append("\n");
            });


            answer = sbAnswer.toString();
*/

            if (isInputFromFile()) {
                System.out.println("\t"+answer);
            }
            callback();
        }

    }

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

    /**
     * Source: http://stackoverflow.com/questions/4521983/java-executorservice-that-blocks-on-submission-after-a-certain-queue-size
     *
     * @param <E>
     */
//    public class LimitedQueue<E> extends LinkedBlockingQueue<E>{
//
//        public LimitedQueue(int maxSize) {
//            super(maxSize);
//        }
//
//        @Override
//        public boolean offer(E e){
//            // turn offer() and add() into a blocking calls (unless interrupted)
//            try {
//                put(e);
//                return true;
//            } catch(InterruptedException ie) {
//                Thread.currentThread().interrupt();
//            }
//            return false;
//        }
//    }

    /**
     * Move to Utilities
     *
     * //List<Integer> primesLimited = getPrimes(1_000_000).subList(0, 100);
     *
     * @param limit
     * @return
     */
    public static List<Integer> getPrimes(int limit) {
        boolean[] primes = new boolean[limit+1];
        Arrays.fill(primes, true);

        primes[1] = false;
        for(int i=2; i<=limit; i++){
            if (primes[i]){
                for(int j=i+i; j<=limit; j+=i){
                    primes[j] = false;
                }
            }
        }
        List<Integer> listPrimes = new ArrayList<>();
        for(int i=2; i<=limit; i++){
            if (primes[i]){
                listPrimes.add(i);
            }
        }
        return listPrimes;
    }


    public static class Modulo{
        long mod = (long)1e9+7;

        public Modulo(long mod) {
            super();
            this.mod = mod;
        }

        public long inv(long a) {
            long res =  pow(a, mod-2);
            return res;
        }

        public long pow(long a, long x) {
            if (x==0)
                return 1;
            long part = 1;
            if ((x&1)!=0)
                part = a;
            return (part * pow((a*a)%mod, x>>1)) % mod;
        }

        public long c(long n, long m){
            long res = 1;
            for(int i=1; i<=m; i++){
                res = (res * (n-m+i)) % mod;
                res = (res * inv(i)) % mod;
            }
            return res;
        }
    }

    /**
     * Added 26.04.2013.
     * See KROK 2013, Round 1, Problem D.
     */
    static class DisjointUnionSet implements Cloneable{
        int[] rank;
        int[] parent;

        protected DisjointUnionSet clone(){
            DisjointUnionSet cloned = new DisjointUnionSet(parent.length);
            for(int i=0; i<parent.length; i++){
                cloned.parent[i] = parent[i];
                cloned.rank[i] = rank[i];
            }
            return cloned;
        }

        public DisjointUnionSet(int n) {
            rank = new int[n];
            parent = new int[n];
            for (int i = 0; i < n; i++) {
                parent[i] = i;
            }
        }

        @Override
        public String toString() {
            return "disj [parents=" + Arrays.toString(parent) + "]";
        }

        /**
         * Problem specific or general?
         * O(N * alpha)
         */
        public void union(DisjointUnionSet set2){
            for(int i=0; i<parent.length; i++){
                parent[find(i)] = parent[find(set2.find(i))];
            }
        }

        /**
         * @param index1 range 0..n-1
         * @param index2
         */
        public void union(int index1, int index2){
            int p1 = find(index1);
            int p2 = find(index2);
            if (rank[p1] > rank[p2]){
                parent[p2] = p1;
            }else if (rank[p2] > rank[p1]){
                parent[p1] = p2;
            }else{
                parent[p2] = p1;
                rank[p1]++;
            }
        }

        // O(alpha(n))
        private int find(int index) {
            if (parent[index] != index)
                parent[index] =  find(parent[index]);
            return parent[index];
        }

        // O(N alpha(N)) ==> see find()
        public int getCountDisjointSets(){
            int[] used = new int[parent.length];
            for(int i=0; i<parent.length; i++){
                used[find(i)] = 1;
            }
            int res = 0;
            for(int i=0; i<parent.length; i++){
                res += used[i];
            }
            return res;
        }
    }

    private static Random rnd = new Random();
    public static class ArrayUtils{
        public static void shuffle(int[] a){
            for(int j=a.length-1; j>=1; j--){
                int i = rnd.nextInt(j+1);
                swap(a, i, j);
            }
        }

        public static void swap(int[] a, int i, int j){
            int tmp = a[i];
            a[i] = a[j];
            a[j] = tmp;
        }
    }

    ////////////////////////////////////////////////////////
    /// Typically, you don't want to edit anything below
    ///////////////////////////////////////////////////////
    final int BUF_SIZE = 1024 * 1024 * 8;//important to read long-string tokens properly
    final int INPUT_BUFFER_SIZE = 1024 * 1024 * 8 ;
    final int BUF_SIZE_INPUT = 1024;

    final int BUF_SIZE_OUT = 1024;

    boolean useClassResourceTopDir = true;
    String outSuffix = ".out";

    //InputStream bis;
    //OutputStream bos;
    static PrintStream out;
    static ByteScanner scanner;
    static ByteWriter writer;

    public void run() {
        try{
            InputStream bis = null;
            OutputStream bos = null;
            if (inputFilename !=null){

                File inputFile = null;
                File outputFile = null;
                if (useClassResourceTopDir) {
                    File baseFile = new File(getClass().getResource("/").getFile());
                    inputFile = new File(baseFile, inputFilename);
                    outputFile = new File(baseFile, inputFilename +outSuffix);
                }else{
                    inputFile = new File(inputFilename);
                    outputFile = new File(inputFilename +outSuffix);
                }
                System.out.println("Input file canonical path: "+inputFile.getCanonicalPath());
                bis = new BufferedInputStream(
                        new FileInputStream(inputFile),
                        INPUT_BUFFER_SIZE);
                bos = new BufferedOutputStream(new FileOutputStream(outputFile));
                out = new PrintStream(bos);
            }else{
                bis = new BufferedInputStream(System.in, INPUT_BUFFER_SIZE);
                bos = new BufferedOutputStream(System.out);
                out = new PrintStream(bos);
            }
            scanner = new ByteScanner(bis, BUF_SIZE_INPUT, BUF_SIZE);
            writer = new ByteWriter(bos, BUF_SIZE_OUT);

            solveAll();
            out.flush();
        }catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    public interface Constants{
        byte ZERO = '0';//48 or 0x30
        byte NINE = '9';
        byte SPACEBAR = ' '; //32 or 0x20
        byte MINUS = '-'; //45 or 0x2d

        char FLOAT_POINT = '.';
    }

    public static class EofException extends IOException{
    }

    public static class ByteWriter implements Constants {

        int bufSize = 1024;
        byte[] byteBuf = new byte[bufSize];
        OutputStream os;

        public ByteWriter(OutputStream os, int bufSize){
            this.os = os;
            this.bufSize = bufSize;
        }

        public void writeInt(int num) throws IOException{
            int byteWriteOffset = byteBuf.length;
            if (num==0){
                byteBuf[--byteWriteOffset] = ZERO;
            }else{
                int numAbs = Math.abs(num);
                while (numAbs>0){
                    byteBuf[--byteWriteOffset] = (byte)((numAbs % 10) + ZERO);
                    numAbs /= 10;
                }
                if (num<0)
                    byteBuf[--byteWriteOffset] = MINUS;
            }
            os.write(byteBuf, byteWriteOffset, byteBuf.length - byteWriteOffset);
        }

        /**
         * Please ensure ar.length <= byteBuf.length!
         *
         * @param ar
         * @throws IOException
         */
        public void writeByteAr(byte[] ar) throws IOException{
            for (int i = 0; i < ar.length; i++) {
                byteBuf[i] = ar[i];
            }
            os.write(byteBuf,0,ar.length);
        }

        public void writeSpaceBar() throws IOException{
            byteBuf[0] = SPACEBAR;
            os.write(byteBuf,0,1);
        }

    }

    public static class ByteScanner implements Constants{

        InputStream is;

        public ByteScanner(InputStream is, int bufSizeInput, int bufSize){
            this.is = is;
            this.bufSizeInput = bufSizeInput;
            this.bufSize = bufSize;

            byteBufInput = new byte[this.bufSizeInput];
            byteBuf = new byte[this.bufSize];
        }

        public ByteScanner(byte[] data){
            byteBufInput = data;
            bufSizeInput = data.length;
            bufSize = data.length;
            byteBuf = new byte[bufSize];
            byteRead = data.length;
            bytePos = 0;
        }

        private int bufSizeInput;
        private int bufSize;

        byte[] byteBufInput;
        byte by=-1;
        int byteRead=-1;
        int bytePos=-1;

        byte[] byteBuf;
        int totalBytes;

        boolean eofMet = false;

        private byte nextByte() throws IOException{

            if (bytePos<0 || bytePos>=byteRead){
                byteRead = is==null? -1: is.read(byteBufInput);
                bytePos=0;
                if (byteRead<0){
                    byteBufInput[bytePos]=-1;//!!!
                    if (eofMet)
                        throw new EofException();
                    eofMet = true;
                }
            }
            return byteBufInput[bytePos++];
        }

        /**
         * Returns the next meaningful character as byte.<br>
         *
         * @return
         * @throws IOException
         */
        public byte nextChar() throws IOException{
            while ((by=nextByte())<=0x20);
            return by;
        }

        /**
         * Returns the next meaningful character OR space as byte.<br>
         *
         * @return
         * @throws IOException
         */
        public byte nextCharOrSpacebar() throws IOException{
            while ((by=nextByte())<0x20);
            return by;
        }

        /**
         * Reads line.
         *
         * @return
         * @throws IOException
         */
        public String nextLine() throws IOException {
            readToken((byte)0x20);
            return new String(byteBuf,0,totalBytes);
        }

        public byte[] nextLineAsArray() throws IOException {
            readToken((byte)0x20);
            byte[] out = new byte[totalBytes];
            System.arraycopy(byteBuf, 0, out, 0, totalBytes);
            return out;
        }

        /**
         * Reads token. Spacebar is separator char.
         *
         * @return
         * @throws IOException
         */
        public String nextToken() throws IOException {
            readToken((byte)0x21);
            return new String(byteBuf,0,totalBytes);
        }

        /**
         * Spacebar is included as separator char
         *
         * @throws IOException
         */
        private void readToken() throws IOException {
            readToken((byte)0x21);
        }

        private void readToken(byte acceptFrom) throws IOException {
            totalBytes = 0;
            while ((by=nextByte())<acceptFrom);
            byteBuf[totalBytes++] = by;
            while ((by=nextByte())>=acceptFrom){
                byteBuf[totalBytes++] = by;
            }
        }

        public int nextInt() throws IOException{
            readToken();
            int num=0, i=0;
            boolean sign=false;
            if (byteBuf[i]==MINUS){
                sign = true;
                i++;
            }
            for (; i<totalBytes; i++){
                num*=10;
                num+=byteBuf[i]-ZERO;
            }
            return sign?-num:num;
        }

        public long nextLong() throws IOException{
            readToken();
            long num=0;
            int i=0;
            boolean sign=false;
            if (byteBuf[i]==MINUS){
                sign = true;
                i++;
            }
            for (; i<totalBytes; i++){
                num*=10;
                num+=byteBuf[i]-ZERO;
            }
            return sign?-num:num;
        }

		/*
		//TODO test Unix/Windows formats
		public void toNextLine() throws IOException{
			while ((ch=nextChar())!='\n');
		}
		*/

        public double nextDouble() throws IOException{
            readToken();
            char[] token = new char[totalBytes];
            for (int i = 0; i < totalBytes; i++) {
                token[i] = (char)byteBuf[i];
            }
            return Double.parseDouble(new String(token));
        }

        public int[] loadIntArray(int size) throws IOException{
            int[] a = new int[size];
            for (int i = 0; i < a.length; i++) {
                a[i] = nextInt();
            }
            return a;
        }

        public long[] loadLongArray(int size) throws IOException{
            long[] a = new long[size];
            for (int i = 0; i < a.length; i++) {
                a[i] = nextLong();
            }
            return a;
        }
    }

    public static void main(String[] args) {
        new CF392_Div2_E().run();
    }
}