Problem: You need to find a binary tree of size n that satisfies a given set of c constraints. Suppose that the nodes of the unknown binary tree are labeled using a pre-order traversal starting with 1. For the i-th constraint you are given two labels, ai and bi and a direction, left or right. In case of left direction, bi is an element of the subtree rooted at ai's left child. Similarly in the case of right direction bi is an element of the subtree rooted at ai's right child.

Input

The first line of input contains two integers n and c. The next c lines contain 2 integers ai, bi (1 ≤ ai, bi ≤ n) and either "LEFT" or "RIGHT" denoting whether b is in the subtree rooted at ai's left child or in the subtree rooted at ai's right child.

The problem consists of multiple subproblems. The subproblems have different constraints on the input. You will get some score for the correct submission of the subproblem. The description of the subproblems follows.

  * In subproblem D1 (9 points), the constraints 1 ≤ n ≤ 100, 1 ≤ c ≤ 50 will hold. 
  * In subproblem D2 (8 points), the constraints 1 ≤ n ≤ 1000000, 1 ≤ c ≤ 100000 will hold. 

Output

Output will be on a single line.

Any binary tree that satisfies the constraints will be accepted. The tree's nodes should be printed out as n space separated labels representing an in-order traversal, using the pre-order numbers as labels of vertices.

If there are no trees that satisfy the constraints, print "IMPOSSIBLE" (without quotes).

Examples

Input

3 2
1 2 LEFT
1 3 RIGHT


Output

2 1 3


Input

3 2
1 2 RIGHT
1 3 LEFT


Output

IMPOSSIBLE

Note

Consider the first sample test. We need to find a tree with 3 nodes that satisfies the following two constraints. The node labeled 2 with pre-order traversal should be in the left subtree of the node labeled 1 with pre-order traversal; the node labeled 3 with pre-order traversal should be in the right subtree of the node labeled 1. There is only one tree with three nodes that satisfies these constraints and its in-order traversal is (2, 1, 3).

Pre-order is the "root – left subtree – right subtree" order. In-order is the "left subtree – root – right subtree" order.

For other information regarding in-order and pre-order, see <http://en.wikipedia.org/wiki/Tree_traversal>.

Solution (in JAVA):

Solution:
import java.io.BufferedWriter;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;
import java.util.List;
import java.math.BigInteger;
import java.io.OutputStream;
import java.util.Iterator;
import java.io.PrintWriter;
import java.io.Writer;
import java.util.Collections;
import java.io.IOException;
import java.util.Arrays;
import java.util.AbstractList;
import java.io.InputStream;
import java.util.Random;
import java.util.Map;
import java.io.OutputStreamWriter;
import java.util.AbstractMap;
import java.util.Comparator;
import java.util.AbstractSet;
import java.util.Set;
import java.util.RandomAccess;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Nguyen Trung Hieu - vuondenthanhcong11@gmail.com
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        TaskD2 solver = new TaskD2();
        solver.solve(1, in, out);
        out.close();
    }
}

class TaskD2 {
    int at;
    int[] answer;
    Graph graph;
    IntervalTree tree;
    int[] qStart;
    int[] qEnd;
    int[] qStartAt;
    public void solve(int testNumber, InputReader in, OutputWriter out) {
        int count = in.readInt();
        qStart = new int[count];
        qEnd = new int[count];
        qStartAt = new int[count];
        int constraintCount = in.readInt();
        int[] parent = new int[constraintCount];
        int[] child = new int[constraintCount];
        graph = new Graph(count, constraintCount);
        boolean[] toRight = new boolean[constraintCount];
        for (int i = 0; i < constraintCount; i++) {
            parent[i] = in.readInt() - 1;
            child[i] = in.readInt() - 1;
            toRight[i] = in.readString().charAt(0) == 'R';
            if (parent[i] >= child[i]) {
                out.printLine("IMPOSSIBLE");
                return;
            }
            graph.addWeightedEdge(parent[i], child[i], toRight[i] ? 1 : -1);
        }
        tree = new LongIntervalTree(count) {
            protected long joinValue(long left, long right) {
                return Math.max(left, right);
            }

            protected long joinDelta(long was, long delta) {
                return Math.max(was, delta);
            }

            protected long accumulate(long value, long delta, int length) {
                return Math.max(value, delta);
            }

            protected long neutralValue() {
                return -1;
            }

            protected long neutralDelta() {
                return -1;
            }

            protected long initValue(int index) {
                return index;
            }
        };
        int[] order = ArrayUtils.order(parent);
        ArrayUtils.reverse(order);
        for (int i : order) {
            tree.update(parent[i], parent[i], tree.query(parent[i], child[i]));
        }
        answer = new int[count];
        qEnd[0] = count - 1;
        at = 1;
        for (int i = 0; i < count; i++) {
            if (!solve(qStart[i], qEnd[i], qStartAt[i])) {
                out.printLine("IMPOSSIBLE");
                return;
            }
        }
        out.printLine(answer);
    }

    boolean solve(int start, int end, int startAt) {
        if (start == end) {
            answer[startAt] = start + 1;
            return true;
        }
        int rightStart = start + 1;
        for (int i = graph.firstOutbound(start); i != -1; i = graph.nextOutbound(i)) {
            if (graph.weight(i) == -1) {
                rightStart = (int) Math.max(rightStart, tree.query(start + 1, graph.destination(i)) + 1);
            }
        }
        for (int i = graph.firstOutbound(start); i != -1; i = graph.nextOutbound(i)) {
            if (graph.weight(i) == 1 && graph.destination(i) < rightStart) {
                return false;
            }
        }
        if (rightStart - 1 >= start + 1) {
            qStart[at] = start + 1;
            qEnd[at] = rightStart - 1;
            qStartAt[at++] = startAt;
        }
        if (end >= rightStart) {
            qStart[at] = rightStart;
            qEnd[at] = end;
            qStartAt[at++] = rightStart - start + startAt;
        }
        answer[rightStart - start - 1 + startAt] = start + 1;
        return true;
    }
}

class Graph {
    public static final int REMOVED_BIT = 0;

    protected int vertexCount;
    protected int edgeCount;

    private int[] firstOutbound;
    private int[] firstInbound;

    private Edge[] edges;
    private int[] nextInbound;
    private int[] nextOutbound;
    private int[] from;
    private int[] to;
    private long[] weight;
    private long[] capacity;
    private int[] reverseEdge;
    private int[] flags;

    public Graph(int vertexCount, int edgeCapacity) {
        this.vertexCount = vertexCount;
        firstOutbound = new int[vertexCount];
        Arrays.fill(firstOutbound, -1);

        from = new int[edgeCapacity];
        to = new int[edgeCapacity];
        nextOutbound = new int[edgeCapacity];
        flags = new int[edgeCapacity];
    }

    public int addEdge(int fromID, int toID, long weight, long capacity, int reverseEdge) {
        ensureEdgeCapacity(edgeCount + 1);
        if (firstOutbound[fromID] != -1)
            nextOutbound[edgeCount] = firstOutbound[fromID];
        else
            nextOutbound[edgeCount] = -1;
        firstOutbound[fromID] = edgeCount;
        if (firstInbound != null) {
            if (firstInbound[toID] != -1)
                nextInbound[edgeCount] = firstInbound[toID];
            else
                nextInbound[edgeCount] = -1;
            firstInbound[toID] = edgeCount;
        }
        this.from[edgeCount] = fromID;
        this.to[edgeCount] = toID;
        if (capacity != 0) {
            if (this.capacity == null)
                this.capacity = new long[from.length];
            this.capacity[edgeCount] = capacity;
        }
        if (weight != 0) {
            if (this.weight == null)
                this.weight = new long[from.length];
            this.weight[edgeCount] = weight;
        }
        if (reverseEdge != -1) {
            if (this.reverseEdge == null) {
                this.reverseEdge = new int[from.length];
                Arrays.fill(this.reverseEdge, 0, edgeCount, -1);
            }
            this.reverseEdge[edgeCount] = reverseEdge;
        }
        if (edges != null)
            edges[edgeCount] = createEdge(edgeCount);
        return edgeCount++;
    }

    protected final GraphEdge createEdge(int id) {
        return new GraphEdge(id);
    }

    public final int addFlowWeightedEdge(int from, int to, long weight, long capacity) {
        if (capacity == 0) {
            return addEdge(from, to, weight, 0, -1);
        } else {
            int lastEdgeCount = edgeCount;
            addEdge(to, from, -weight, 0, lastEdgeCount + entriesPerEdge());
            return addEdge(from, to, weight, capacity, lastEdgeCount);
        }
    }

    protected int entriesPerEdge() {
        return 1;
    }

    public final int addWeightedEdge(int from, int to, long weight) {
        return addFlowWeightedEdge(from, to, weight, 0);
    }

    public final int destination(int id) {
        return to[id];
    }

    public final boolean flag(int id, int bit) {
        return (flags[id] >> bit & 1) != 0;
    }

    public final boolean isRemoved(int id) {
        return flag(id, REMOVED_BIT);
    }

    protected void ensureEdgeCapacity(int size) {
        if (from.length < size) {
            int newSize = Math.max(size, 2 * from.length);
            if (edges != null)
                edges = resize(edges, newSize);
            from = resize(from, newSize);
            to = resize(to, newSize);
            nextOutbound = resize(nextOutbound, newSize);
            if (nextInbound != null)
                nextInbound = resize(nextInbound, newSize);
            if (weight != null)
                weight = resize(weight, newSize);
            if (capacity != null)
                capacity = resize(capacity, newSize);
            if (reverseEdge != null)
                reverseEdge = resize(reverseEdge, newSize);
            flags = resize(flags, newSize);
        }
    }

    protected final int[] resize(int[] array, int size) {
        int[] newArray = new int[size];
        System.arraycopy(array, 0, newArray, 0, array.length);
        return newArray;
    }

    private long[] resize(long[] array, int size) {
        long[] newArray = new long[size];
        System.arraycopy(array, 0, newArray, 0, array.length);
        return newArray;
    }

    private Edge[] resize(Edge[] array, int size) {
        Edge[] newArray = new Edge[size];
        System.arraycopy(array, 0, newArray, 0, array.length);
        return newArray;
    }

    protected class GraphEdge implements Edge {
        protected int id;

        protected GraphEdge(int id) {
            this.id = id;
        }

    }

    public final int firstOutbound(int vertex) {
        int id = firstOutbound[vertex];
        while (id != -1 && isRemoved(id))
            id = nextOutbound[id];
        return id;
    }

    public final long weight(int id) {
        if (weight == null)
            return 0;
        return weight[id];
    }

    public final int nextOutbound(int id) {
        id = nextOutbound[id];
        while (id != -1 && isRemoved(id))
            id = nextOutbound[id];
        return id;
    }

}

abstract class IntervalTree {
    protected int size;

    public IntervalTree(int size, boolean shouldInit) {
        this.size = size;
        int nodeCount = Math.max(1, Integer.highestOneBit(size) << 2);
        initData(size, nodeCount);
        if (shouldInit)
            init();
    }

    protected abstract void initData(int size, int nodeCount);
    protected abstract void initAfter(int root, int left, int right, int middle);
    protected abstract void initBefore(int root, int left, int right, int middle);
    protected abstract void initLeaf(int root, int index);
    protected abstract void updatePostProcess(int root, int left, int right, int from, int to, long delta, int middle);
    protected abstract void updatePreProcess(int root, int left, int right, int from, int to, long delta, int middle);
    protected abstract void updateFull(int root, int left, int right, int from, int to, long delta);
    protected abstract long queryPostProcess(int root, int left, int right, int from, int to, int middle, long leftResult, long rightResult);
    protected abstract void queryPreProcess(int root, int left, int right, int from, int to, int middle);
    protected abstract long queryFull(int root, int left, int right, int from, int to);
    protected abstract long emptySegmentResult();

    public void init() {
        if (size == 0)
            return;
        init(0, 0, size - 1);
    }

    private void init(int root, int left, int right) {
        if (left == right) {
            initLeaf(root, left);
        } else {
            int middle = (left + right) >> 1;
            initBefore(root, left, right, middle);
            init(2 * root + 1, left, middle);
            init(2 * root + 2, middle + 1, right);
            initAfter(root, left, right, middle);
        }
    }

    public void update(int from, int to, long delta) {
        update(0, 0, size - 1, from, to, delta);
    }

    protected void update(int root, int left, int right, int from, int to, long delta) {
        if (left > to || right < from)
            return;
        if (left >= from && right <= to) {
            updateFull(root, left, right, from, to, delta);
            return;
        }
        int middle = (left + right) >> 1;
        updatePreProcess(root, left, right, from, to, delta, middle);
        update(2 * root + 1, left, middle, from, to, delta);
        update(2 * root + 2, middle + 1, right, from, to, delta);
        updatePostProcess(root, left, right, from, to, delta, middle);
    }

    public long query(int from, int to) {
        return query(0, 0, size - 1, from, to);
    }

    protected long query(int root, int left, int right, int from, int to) {
        if (left > to || right < from)
            return emptySegmentResult();
        if (left >= from && right <= to)
            return queryFull(root, left, right, from, to);
        int middle = (left + right) >> 1;
        queryPreProcess(root, left, right, from, to, middle);
        long leftResult = query(2 * root + 1, left, middle, from, to);
        long rightResult = query(2 * root + 2, middle + 1, right, from, to);
        return queryPostProcess(root, left, right, from, to, middle, leftResult, rightResult);
    }
}

class InputReader {
    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;
    private SpaceCharFilter filter;

    public InputReader(InputStream stream) {
        this.stream = stream;
    }

    public int read() {
        if (numChars == -1)
            throw new InputMismatchException();
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }

    public int readInt() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }

    public boolean isSpaceChar(int c) {
        if (filter != null)
            return filter.isSpaceChar(c);
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public String readString() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        StringBuffer res = new StringBuffer();
        do {
            res.appendCodePoint(c);
            c = read();
        } while (!isSpaceChar(c));
        return res.toString();
    }

    public interface SpaceCharFilter {
        public boolean isSpaceChar(int ch);
    }

}

class OutputWriter {
    private final PrintWriter writer;

    public OutputWriter(OutputStream outputStream) {
        writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
    }

    public void print(int[] array) {
        for (int i = 0; i < array.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(array[i]);
        }
    }

    public void printLine(int[] array) {
        print(array);
        writer.println();
    }

    public void print(Object...objects) {
        for (int i = 0; i < objects.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(objects[i]);
        }
    }

    public void printLine(Object...objects) {
        print(objects);
        writer.println();
    }

    public void close() {
        writer.close();
    }

}

abstract class LongIntervalTree extends IntervalTree {
    protected long[] value;
    protected long[] delta;

    protected LongIntervalTree(int size) {
        this(size, true);
    }

    public LongIntervalTree(int size, boolean shouldInit) {
        super(size, shouldInit);
    }

    protected void initData(int size, int nodeCount) {
        value = new long[nodeCount];
        delta = new long[nodeCount];
    }

    protected abstract long joinValue(long left, long right);
    protected abstract long joinDelta(long was, long delta);
    protected abstract long accumulate(long value, long delta, int length);
    protected abstract long neutralValue();
    protected abstract long neutralDelta();

    protected long initValue(int index) {
        return neutralValue();
    }

    protected void initAfter(int root, int left, int right, int middle) {
        value[root] = joinValue(value[2 * root + 1], value[2 * root + 2]);
        delta[root] = neutralDelta();
    }

    protected void initBefore(int root, int left, int right, int middle) {
    }

    protected void initLeaf(int root, int index) {
        value[root] = initValue(index);
        delta[root] = neutralDelta();
    }

    protected void updatePostProcess(int root, int left, int right, int from, int to, long delta, int middle) {
        value[root] = joinValue(value[2 * root + 1], value[2 * root + 2]);
    }

    protected void updatePreProcess(int root, int left, int right, int from, int to, long delta, int middle) {
        pushDown(root, left, middle, right);
    }

    protected void pushDown(int root, int left, int middle, int right) {
        value[2 * root + 1] = accumulate(value[2 * root + 1], delta[root], middle - left + 1);
        value[2 * root + 2] = accumulate(value[2 * root + 2], delta[root], right - middle);
        delta[2 * root + 1] = joinDelta(delta[2 * root + 1], delta[root]);
        delta[2 * root + 2] = joinDelta(delta[2 * root + 2], delta[root]);
        delta[root] = neutralDelta();
    }

    protected void updateFull(int root, int left, int right, int from, int to, long delta) {
        value[root] = accumulate(value[root], delta, right - left + 1);
        this.delta[root] = joinDelta(this.delta[root], delta);
    }

    protected long queryPostProcess(int root, int left, int right, int from, int to, int middle, long leftResult, long rightResult) {
        return joinValue(leftResult, rightResult);
    }

    protected void queryPreProcess(int root, int left, int right, int from, int to, int middle) {
        pushDown(root, left, middle, right);
    }

    protected long queryFull(int root, int left, int right, int from, int to) {
        return value[root];
    }

    protected long emptySegmentResult() {
        return neutralValue();
    }
}

class ArrayUtils {

    public static int[] createOrder(int size) {
        int[] order = new int[size];
        for (int i = 0; i < size; i++)
            order[i] = i;
        return order;
    }

    public static int[] sort(int[] array, IntComparator comparator) {
        return sort(array, 0, array.length, comparator);
    }

    public static int[] sort(int[] array, int from, int to, IntComparator comparator) {
        if (from == 0 && to == array.length)
            new IntArray(array).inPlaceSort(comparator);
        else
            new IntArray(array).subList(from, to).inPlaceSort(comparator);
        return array;
    }

    public static void reverse(int[] array) {
        reverse(array, 0, array.length);
    }

    public static void reverse(int[] array, int from, int to) {
        for (int i = from, j = to - 1; i < j; i++, j--) {
            int temp = array[i];
            array[i] = array[j];
            array[j] = temp;
        }
    }

    public static int[] order(final int[] array) {
        return sort(createOrder(array.length), new IntComparator() {
            public int compare(int first, int second) {
                if (array[first] < array[second])
                    return -1;
                if (array[first] > array[second])
                    return 1;
                return 0;
            }
        });
    }

    /*Them boi Nguyen Trung Hieu*/


    //update 24/8/2013


}

interface Edge {
}

abstract class IntCollection {
    public abstract IntIterator iterator();
    public abstract int size();

}

interface IntIterator {
    public int value() throws NoSuchElementException;
    /*
     * @throws NoSuchElementException only if iterator already invalid
     */
    public void advance() throws NoSuchElementException;
    public boolean isValid();
}

interface IntComparator {

    public int compare(int first, int second);
}

abstract class IntList extends IntCollection implements Comparable<IntList> {
    private static final int INSERTION_THRESHOLD = 8;

    public abstract int get(int index);
    public abstract void set(int index, int value);

    public IntIterator iterator() {
        return new IntIterator() {
            private int size = size();
            private int index = 0;

            public int value() throws NoSuchElementException {
                if (!isValid())
                    throw new NoSuchElementException();
                return get(index);
            }

            public void advance() throws NoSuchElementException {
                if (!isValid())
                    throw new NoSuchElementException();
                index++;
            }

            public boolean isValid() {
                return index < size;
            }
        };
    }

    public IntList subList(final int from, final int to) {
        return new SubList(from, to);
    }

    private void swap(int first, int second) {
        if (first == second)
            return;
        int temp = get(first);
        set(first, get(second));
        set(second, temp);
    }

    public IntSortedList inPlaceSort(IntComparator comparator) {
        quickSort(0, size() - 1, size(), comparator);
        return new IntSortedArray(this, comparator);
    }

    private void quickSort(int from, int to, int remaining, IntComparator comparator) {
        if (to - from < INSERTION_THRESHOLD) {
            insertionSort(from, to, comparator);
            return;
        }
        if (remaining == 0) {
            heapSort(from, to, comparator);
            return;
        }
        remaining >>= 1;
        int pivotIndex = (from + to) >> 1;
        int pivot = get(pivotIndex);
        swap(pivotIndex, to);
        int storeIndex = from;
        int equalIndex = to;
        for (int i = from; i < equalIndex; i++) {
            int value = comparator.compare(get(i), pivot);
            if (value < 0)
                swap(storeIndex++, i);
            else if (value == 0)
                swap(--equalIndex, i--);
        }
        quickSort(from, storeIndex - 1, remaining, comparator);
        for (int i = equalIndex; i <= to; i++)
            swap(storeIndex++, i);
        quickSort(storeIndex, to, remaining, comparator);
    }

    private void heapSort(int from, int to, IntComparator comparator) {
        for (int i = (to + from - 1) >> 1; i >= from; i--)
            siftDown(i, to, comparator, from);
        for (int i = to; i > from; i--) {
            swap(from, i);
            siftDown(from, i - 1, comparator, from);
        }
    }

    private void siftDown(int start, int end, IntComparator comparator, int delta) {
        int value = get(start);
        while (true) {
            int child = ((start - delta) << 1) + 1 + delta;
            if (child > end)
                return;
            int childValue = get(child);
            if (child + 1 <= end) {
                int otherValue = get(child + 1);
                if (comparator.compare(otherValue, childValue) > 0) {
                    child++;
                    childValue = otherValue;
                }
            }
            if (comparator.compare(value, childValue) >= 0)
                return;
            swap(start, child);
            start = child;
        }
    }

    private void insertionSort(int from, int to, IntComparator comparator) {
        for (int i = from + 1; i <= to; i++) {
            int value = get(i);
            for (int j = i - 1; j >= from; j--) {
                if (comparator.compare(get(j), value) <= 0)
                    break;
                swap(j, j + 1);
            }
        }
    }

    public int hashCode() {
        int hashCode = 1;
        for (IntIterator i = iterator(); i.isValid(); i.advance())
            hashCode = 31 * hashCode + i.value();
        return hashCode;
    }

    public boolean equals(Object obj) {
        if (!(obj instanceof IntList))
            return false;
        IntList list = (IntList)obj;
        if (list.size() != size())
            return false;
        IntIterator i = iterator();
        IntIterator j = list.iterator();
        while (i.isValid()) {
            if (i.value() != j.value())
                return false;
            i.advance();
            j.advance();
        }
        return true;
    }

    public int compareTo(IntList o) {
        IntIterator i = iterator();
        IntIterator j = o.iterator();
        while (true) {
            if (i.isValid()) {
                if (j.isValid()) {
                    if (i.value() != j.value()) {
                        if (i.value() < j.value())
                            return -1;
                        else
                            return 1;
                    }
                } else
                    return 1;
            } else {
                if (j.isValid())
                    return -1;
                else
                    return 0;
            }
            i.advance();
            j.advance();
        }
    }

    public IntSortedList sort(IntComparator comparator) {
        return new IntArray(this).inPlaceSort(comparator);
    }

    private class SubList extends IntList {
        private final int to;
        private final int from;
        private int size;

        public SubList(int from, int to) {
            this.to = to;
            this.from = from;
            size = to - from;
        }

        public int get(int index) {
            if (index < 0 || index >= size)
                throw new IndexOutOfBoundsException();
            return IntList.this.get(index + from);
        }

        public void set(int index, int value) {
            if (index < 0 || index >= size)
                throw new IndexOutOfBoundsException();
            IntList.this.set(index + from, value);
        }

        public int size() {
            return size;
        }

    }


}

abstract class IntSortedList extends IntList {
    protected final IntComparator comparator;

    protected IntSortedList(IntComparator comparator) {
        this.comparator = comparator;
    }

    public void set(int index, int value) {
        throw new UnsupportedOperationException();
    }

    public IntSortedList inPlaceSort(IntComparator comparator) {
        if (comparator == this.comparator)
            return this;
        throw new UnsupportedOperationException();
    }

    public IntSortedList sort(IntComparator comparator) {
        if (comparator == this.comparator)
            return this;
        return super.sort(comparator);
    }

    protected void ensureSorted() {
        int size = size();
        if (size == 0)
            return;
        int last = get(0);
        for (int i = 1; i < size; i++) {
            int current = get(i);
            if (comparator.compare(last, current) > 0)
                throw new IllegalArgumentException();
            last = current;
        }
    }

    public IntSortedList subList(final int from, final int to) {
        return new IntSortedList(comparator) {
            private int size = to - from;

            public int get(int index) {
                if (index < 0 || index >= size)
                    throw new IndexOutOfBoundsException();
                return IntSortedList.this.get(index + from);
            }

            public int size() {
                return size;
            }

        };
    }
}

class IntArray extends IntList {
    private final int[] array;

    public IntArray(int[] array) {
        this.array = array;
    }

    public IntArray(IntCollection collection) {
        array = new int[collection.size()];
        int i = 0;
        for (IntIterator iterator = collection.iterator(); iterator.isValid(); iterator.advance())
            array[i++] = iterator.value();
    }

    public int get(int index) {
        return array[index];
    }

    public void set(int index, int value) {
        array[index] = value;
    }

    public int size() {
        return array.length;
    }

}

class IntSortedArray extends IntSortedList {
    private final int[] array;

    public IntSortedArray(IntCollection collection, IntComparator comparator) {
        super(comparator);
        array = new int[collection.size()];
        int i = 0;
        for (IntIterator iterator = collection.iterator(); iterator.isValid(); iterator.advance())
            array[i++] = iterator.value();
        ensureSorted();
    }

    public int get(int index) {
        return array[index];
    }

    public int size() {
        return array.length;
    }
}