Kefa decided to celebrate his first big salary by going to the restaurant. 

He lives by an unusual park. The park is a rooted tree consisting of n vertices with the root at vertex 1. Vertex 1 also contains Kefa's house. Unfortunaely for our hero, the park also contains cats. Kefa has already found out what are the vertices with cats in them.

The leaf vertices of the park contain restaurants. Kefa wants to choose a restaurant where he will go, but unfortunately he is very afraid of cats, so there is no way he will go to the restaurant if the path from the restaurant to his house contains more than m consecutive vertices with cats. 

Your task is to help Kefa count the number of restaurants where he can go.

Input

The first line contains two integers, n and m (2 ≤ n ≤ 105, 1 ≤ m ≤ n) — the number of vertices of the tree and the maximum number of consecutive vertices with cats that is still ok for Kefa.

The second line contains n integers a1, a2, ..., an, where each ai either equals to 0 (then vertex i has no cat), or equals to 1 (then vertex i has a cat).

Next n - 1 lines contains the edges of the tree in the format "xi yi" (without the quotes) (1 ≤ xi, yi ≤ n, xi ≠ yi), where xi and yi are the vertices of the tree, connected by an edge. 

It is guaranteed that the given set of edges specifies a tree.

Output

A single integer — the number of distinct leaves of a tree the path to which from Kefa's home contains at most m consecutive vertices with cats.

Examples

Input

4 1
1 1 0 0
1 2
1 3
1 4


Output

2


Input

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


Output

2

Note

Let us remind you that a tree is a connected graph on n vertices and n - 1 edge. A rooted tree is a tree with a special vertex called root. In a rooted tree among any two vertices connected by an edge, one vertex is a parent (the one closer to the root), and the other one is a child. A vertex is called a leaf, if it has no children.

Note to the first sample test: <image> The vertices containing cats are marked red. The restaurants are at vertices 2, 3, 4. Kefa can't go only to the restaurant located at vertex 2.

Note to the second sample test: <image> The restaurants are located at vertices 4, 5, 6, 7. Kefa can't go to restaurants 6, 7.
import javafx.util.Pair;

import java.io.*;
import java.util.*;
import java.util.function.Function;

public class Main {
    private final static InputReader ir = new InputReader(System.in);
    private final static OutputWriter ow = new OutputWriter(System.out);
    private final static int INF = Integer.MAX_VALUE;
    private final static int NINF = Integer.MIN_VALUE;
    private final static double PI = Math.PI;

    public static void main(String[] args) throws IOException {
        try {
            task();
        } finally {
            boolean exc = false;
            try {
                ir.close();
            } catch (IOException e) {
                e.printStackTrace();
                exc = true;
            }
            try {
                ow.close();
            } catch (IOException e) {
                e.printStackTrace();
                exc = true;
            }
            if (exc) System.exit(1);
        }
    }

    static ArrayList<LinkedList<Integer>> graph;
    static boolean[] used;
    static boolean[] a;
    static int m;
    static int cnt = 0;

    static void dfs(int x, int cntCats) {
        used[x] = true;
        //System.out.println(x);
        if (a[x])
            cntCats = cntCats + 1;
        else cntCats = 0;


        if (x != 0 && graph.get(x).size() == 1 && cntCats <= m) {
            ++cnt;
            return;
        }

        for (Integer y : graph.get(x)) {
            if (!used[y]) {
                if (cntCats <= m) dfs(y, cntCats);
            }
        }
    }

    private static void task() throws IOException {
        int n = ir.nextInt();
        m = ir.nextInt();
        a = new boolean[n];
        for (int i = 0; i < n; ++i) {
            a[i] = (ir.nextInt() == 1);
        }

        graph = new ArrayList<>(n);
        for (int i = 0; i < n; ++i) {
            graph.add(new LinkedList<>());
        }
        used = new boolean[n];
        for (int i = 0; i < n - 1; ++i) {
            int xi = ir.nextInt() - 1;
            int yi = ir.nextInt() - 1;
            graph.get(xi).add(yi);
            graph.get(yi).add(xi);
        }
//        for (int i = 0; i < n; ++i) {
//            for (int j = 0; j < graph.get(i).size(); ++j)
//                System.out.print(graph.get(i).get(j));
//            System.out.println();
//        }
        dfs(0, 0);
        ow.print(cnt);
    }

    private static int max(int... objects) {
        if (objects.length == 0)
            throw new IllegalArgumentException("objects.length == 0");
        int max = objects[0];
        for (int i = 1; i < objects.length; ++i) {
            if (max < objects[i])
                max = objects[i];
        }
        return max;
    }

    private static int min(int... objects) {
        if (objects.length == 0)
            throw new IllegalArgumentException("objects.length == 0");
        int min = objects[0];
        for (int i = 1; i < objects.length; ++i) {
            if (min > objects[i])
                min = objects[i];
        }
        return min;
    }

    private static long pow(int x, int n) {
        if (x == 0) return 0;
        if (x == 1 || n == 0) return 1;
        if (x == 2) return x << (n - 1);
        if (n == 1) return x;
        long t = pow(x, n / 2);
        if (n % 2 == 0) return t * t;
        else return t * t * x;
    }

    private static double pow(double x, int n) {
        if (x == 0.0) return 0;
        if (x == 1.0 || n == 0) return 1;
        if (n == 1) return x;
        double t = pow(x, n / 2);
        if (n % 2 == 0) return t * t;
        else return t * t * x;
    }

    private static int abs(int a) {
        return (a >= 0 ? a : -a);
    }
}

class SQRTDecomposition {
    private int[] array;
    private int len;
    private int[] max;
    private int[] min;

    public SQRTDecomposition(int[] arr, boolean useIt) {
        if (useIt)
            array = arr;
        else {
            array = new int[arr.length];
            System.arraycopy(arr, 0, array, 0, arr.length);
        }
        len = (int) Math.sqrt(array.length) + 1;
        max = new int[len];
        min = new int[len];
        for (int i = 0; i < array.length; ++i) {
            max[i / len] = min[i / len] = array[i];
        }
        for (int i = 0; i < array.length; ++i) {
            max[i / len] = Math.max(max[i / len], array[i]);
            min[i / len] = Math.min(min[i / len], array[i]);
        }
    }

    public int get(int i) {
        if (i <= 0 || i >= array.length)
            throw new IndexOutOfBoundsException("Index: " + i);
        return array[i];
    }

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

    public int max(int l, int r) {
        int cl = l / len, cr = r / len;
        int m = array[l];
        if (cl == cr) {
            for (int i = l; i <= r; ++i) {
                if (array[i] > m) m = array[i];
            }
        } else {
            for (int i = l, end = (cl + 1) * len - 1; i <= end; ++i)
                if (array[i] > m) m = array[i];
            for (int i = cl + 1; i <= cr - 1; ++i)
                if (max[i] > m) m = max[i];
            for (int i = cr * len; i <= r; ++i)
                if (array[i] > m) m = array[i];
        }
        return m;
    }

    public int min(int l, int r) {
        int cl = l / len, cr = r / len;
        int m = array[l];
        if (cl == cr) {
            for (int i = l; i <= r; ++i) {
                if (array[i] < m) m = array[i];
            }
        } else {
            for (int i = l, end = (cl + 1) * len - 1; i <= end; ++i)
                if (array[i] < m) m = array[i];
            for (int i = cl + 1; i <= cr - 1; ++i)
                if (min[i] < m) m = min[i];
            for (int i = cr * len; i <= r; ++i)
                if (array[i] < m) m = array[i];
        }
        return m;
    }
}

class InputReader implements AutoCloseable {
    private final InputStream in;
    private int capacity;
    private byte[] buffer;
    private int len = 0;
    private int cur = 0;

    public InputReader(InputStream stream) {
        this(stream, 100_000);
    }

    public InputReader(InputStream stream, int capacity) {
        this.in = stream;
        this.capacity = capacity;
        buffer = new byte[capacity];
    }

    private boolean update() {
        if (cur >= len) {
            try {
                cur = 0;
                len = in.read(buffer, 0, capacity);
                if (len <= 0)
                    return false;
            } catch (IOException e) {
                throw new InputMismatchException();
            }
        }
        return true;
    }

    private int read() {
        if (update())
            return buffer[cur++];
        else return -1;
    }

    public boolean isEmpty() {
        return !update();
    }

    private boolean isSpace(int c) {
        return c == '\n' || c == '\t' || c == '\r' || c == ' ';
    }

    private boolean isEscape(int c) {
        return c == '\n' || c == '\t' || c == '\r' || c == -1;
    }

    private int readSkipSpace() {
        int c;
        do {
            c = read();
        } while (isSpace(c));
        return c;
    }

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

    public int[] getAllInts() {
        List<Integer> list = new LinkedList<>();
        while (true) {
            try {
                int t = nextInt();
                list.add(t);
            } catch (InputMismatchException e) {
                break;
            }
        }
        int[] a = new int[list.size()];
        Iterator<Integer> it = list.iterator();
        for (int i = 0; it.hasNext(); ++i)
            a[i] = it.next();
        return a;
    }

    public int[] getIntArray1D(int n) {
        int[] array = new int[n];
        for (int i = 0; i < n; ++i) {
            array[i] = nextInt();
        }
        return array;
    }

    public int[][] getIntArray2D(int n, int m) {
        int[][] array = new int[n][m];
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < m; ++j)
                array[i][j] = nextInt();
        }
        return array;
    }

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

    public long[] getAllLongs() {
        List<Long> list = new LinkedList<>();
        while (true) {
            try {
                long t = nextLong();
                list.add(t);
            } catch (InputMismatchException e) {
                break;
            }
        }
        long[] a = new long[list.size()];
        Iterator<Long> it = list.iterator();
        for (int i = 0; it.hasNext(); ++i)
            a[i] = it.next();
        return a;
    }

    public long[] getLongArray1D(int n) {
        long[] array = new long[n];
        for (int i = 0; i < n; ++i) {
            array[i] = nextLong();
        }
        return array;
    }

    public long[][] getLongArray2D(int n, int m) {
        long[][] array = new long[n][m];
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < m; ++j)
                array[i][j] = nextLong();
        }
        return array;
    }

    public int nextChar() {
        int c = readSkipSpace();
        if (c < 0)
            throw new InputMismatchException();
        return c;
    }

    public String nextLine(int initialCapacity) {
        StringBuilder res = new StringBuilder(initialCapacity);
        int c = readSkipSpace();
        do {
            res.append((char) (c));
            c = read();
        } while (!isEscape(c));
        return res.toString();
    }

    @Override
    public void close() throws IOException {
        in.close();
    }
}

class OutputWriter implements Flushable, AutoCloseable {
    private byte[] buf;
    private final int capacity;
    private int count;
    private OutputStream out;

    public OutputWriter(OutputStream stream) {
        this(stream, 10_000);
    }

    public OutputWriter(OutputStream stream, int capacity) {
        if (capacity < 0)
            throw new IllegalArgumentException("capacity < 0");
        out = stream;
        this.capacity = capacity;
        if (capacity != 0) {
            buf = new byte[capacity];
        }
    }

    public void write(int b) throws IOException {
        if (capacity != 0) {
            if (count >= capacity)
                flushBuffer();
            buf[count++] = (byte) b;
        } else {
            out.write(b);
        }
    }

    public void write(byte[] bytes, int off, int len) throws IOException {
        if (capacity != 0) {
            if (len >= capacity) {
                flushBuffer();
                out.write(bytes, off, len);
                return;
            }
            if (len > capacity - count)
                flushBuffer();
            System.arraycopy(bytes, off, buf, count, len);
            count += len;
        } else out.write(bytes, off, len);
    }

    public void write(byte[] bytes) throws IOException {
        write(bytes, 0, bytes.length);
    }

    public void println() throws IOException {
        print("\n");
    }

    public void print(Object object) throws IOException {
        write(String.valueOf(object).getBytes());
    }

    public void println(Object object) throws IOException {
        print(object);
        println();
    }

    public void print(int... ints) throws IOException {
        print(" ", ints);
    }

    public void println(int... ints) throws IOException {
        print(ints);
        println();
    }

    public void println(String separator, int... ints) throws IOException {
        print(separator, ints);
        println();
    }

    public void print(String separator, int... ints) throws IOException {
        if (ints.length == 0) throw new IllegalArgumentException("ints.length == 0");
        for (int i = 0; i < ints.length; ++i) {
            if (i != 0) print(separator);
            print(ints[i]);
        }
    }

    private void flushBuffer() throws IOException {
        if (count > 0) {
            out.write(buf, 0, count);
            count = 0;
        }
    }

    @Override
    public void flush() throws IOException {
        flushBuffer();
        out.flush();
    }

    @Override
    public void close() throws IOException {
        flush();
        out.close();
    }
}
/*
class InputReader implements AutoCloseable {
    private final InputStream in;
    private int capacity;
    private byte[] buffer;
    private int len = 0;
    private int cur = 0;

    public InputReader(InputStream stream) {
        this(stream, 100_000);
    }

    public InputReader(InputStream stream, int capacity) {
        this.in = stream;
        this.capacity = capacity;
        buffer = new byte[capacity];
    }

    private int read() {
        if (cur >= len) {
            try {
                cur = 0;
                len = in.read(buffer, 0, capacity);
                if (len <= 0)
                    return -1;
            } catch (IOException e) {
                throw new InputMismatchException();
            }
        }
        return buffer[cur++];
    }

    private boolean isSpace(int c) {
        return c == ' ' || isEscape(c);
    }

    private boolean isEscape(int c) {
        return c == '\n' || c == '\t' || c == '\r' || c == -1;
    }

    private int readSkipSpace() {
        int c;
        do {
            c = read();
        } while (isSpace(c));
        return c;
    }

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

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

    int nextChar() {
        return readSkipSpace();
    }

    String nextLine(int initialCapacity) {
        StringBuilder res = new StringBuilder(initialCapacity);
        int c = readSkipSpace();
        do {
            res.append((char) (c));
            c = read();
        } while (!isEscape(c));
        return res.toString();
    }

    @Override
    public void close() throws IOException {
        in.close();
    }
}

class OutputWriter implements Flushable, AutoCloseable {
    private byte[] buf;
    private int capacity;
    private int count;
    private OutputStream out;

    public OutputWriter(OutputStream stream) {
        out = stream;
        capacity = 10_000;
        buf = new byte[capacity];
    }

    public OutputWriter(OutputStream stream, int capacity) {
        if (capacity <= 0)
            throw new IllegalArgumentException("capacity <= 0");
        out = stream;
        this.capacity = capacity;
        buf = new byte[capacity];
    }

    public void write(int b) throws IOException {
        if (count >= buf.length)
            flushBuffer();
        buf[count++] = (byte) b;
    }

    public void write(byte[] bytes, int off, int len) throws IOException {
        if (len >= buf.length) {
            flushBuffer();
            out.write(bytes, off, len);
            return;
        }
        if (len > buf.length - count)
            flushBuffer();
        System.arraycopy(bytes, off, buf, count, len);
        count += len;
    }

    public void write(byte[] bytes) throws IOException {
        write(bytes, 0, bytes.length);
    }

    public void print(String str) throws IOException {
        write(str.getBytes());
    }

    public void println() throws IOException {
        print("\n");
    }

    public void print(Object object) throws IOException {
        print(object.toString());
    }

    public void println(Object object) throws IOException {
        print(object.toString());
        println();
    }

    public void print(int... ints) throws IOException {
        print(" ", ints);
    }

    public void println(int... ints) throws IOException {
        print(ints);
        println();
    }

    public void println(String separator, int... ints) throws IOException {
        print(separator, ints);
        println();
    }

    public void print(String separator, int... ints) throws IOException {
        if (ints.length == 0) throw new IllegalArgumentException("ints.length == 0");
        for (int i = 0; i < ints.length; ++i) {
            if (i != 0) print(separator);
            print(ints[i]);
        }
    }

    private void flushBuffer() throws IOException {
        if (count > 0) {
            out.write(buf, 0, count);
            count = 0;
        }
    }

    @Override
    public void flush() throws IOException {
        flushBuffer();
        out.flush();
    }

    @Override
    public void close() throws IOException {
        flush();
        out.close();
    }
}

*/


