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 java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class _580C {

    static int n;
    static int m;
    static boolean[] hasCat, canEat;
    static List<Integer>[] tree;

    static void dfs(int u, int parent, int acc, boolean fucked) {
        boolean isLeaf = true;

        if (hasCat[u]) acc++;
        else acc = 0;
        if (acc > m) fucked = true;

        for (int v : tree[u])
            if (v != parent) {
                dfs(v, u, acc, fucked);
                isLeaf = false;
            }

        if (isLeaf) {
            if (!fucked) canEat[u] = true;
        }
    }

    public static void main(String[] args) throws Exception {
        Reader.init(System.in);
        BufferedWriter cout = new BufferedWriter(new OutputStreamWriter(System.out));

        n = Reader.nextInt();
        m = Reader.nextInt();
        hasCat = new boolean[n];
        canEat = new boolean[n];
        tree = new List[n];
        for (int i = 0; i < n; i++) hasCat[i] = Reader.nextInt() == 1;
        for (int i = 0; i < n; i++) tree[i] = new ArrayList<>(1);
        for (int i = 0; i < n - 1; i++) {
            int u = Reader.nextInt() - 1;
            int v = Reader.nextInt() - 1;
            tree[u].add(v);
            tree[v].add(u);
        }

        dfs(0, -1, 0, false);

        int ans = 0;
        for (int i = 0; i < n; i++) if (canEat[i]) ans++;
        System.out.println(ans);

        cout.close();
    }

    static class Pair<U extends Comparable<U>, V extends Comparable<V>> implements Comparable<Pair<U, V>> {
        final U _1;
        final V _2;

        private Pair(U key, V val) {
            this._1 = key;
            this._2 = val;
        }

        public static <U extends Comparable<U>, V extends Comparable<V>> Pair<U, V> instanceOf(U _1, V _2) {
            return new Pair<U, V>(_1, _2);
        }

        @Override
        public String toString() {
            return _1 + " " + _2;
        }

        @Override
        public int hashCode() {
            int res = 17;
            res = res * 31 + _1.hashCode();
            res = res * 31 + _2.hashCode();
            return res;
        }

        @Override
        public int compareTo(Pair<U, V> that) {
            int res = this._1.compareTo(that._1);
            if (res < 0 || res > 0) return res;
            else return this._2.compareTo(that._2);
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) return true;
            if (!(obj instanceof Pair)) return false;
            Pair<?, ?> that = (Pair<?, ?>) obj;
            return _1.equals(that._1) && _2.equals(that._2);
        }
    }

    /**
     * Class for buffered reading int and double values
     */
    static class Reader {
        static BufferedReader reader;
        static StringTokenizer tokenizer;

        /**
         * call this method to initialize reader for InputStream
         */
        static void init(InputStream input) {
            reader = new BufferedReader(new InputStreamReader(input));
            tokenizer = new StringTokenizer("");
        }

        /**
         * get next word
         */
        static String next() throws IOException {
            while (!tokenizer.hasMoreTokens()) {
                // TODO add check for eof if necessary
                tokenizer = new StringTokenizer(reader.readLine());
            }
            return tokenizer.nextToken();
        }

        static int nextInt() throws IOException {
            return Integer.parseInt(next());
        }

        static double nextDouble() throws IOException {
            return Double.parseDouble(next());
        }
    }

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

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

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

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

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

        static void reverse(int[] a, int i, int j) {
            for (; i < j; i++, j--)
                swap(a, i, j);
        }

        static void reverse(long[] a, int i, int j) {
            for (; i < j; i++, j--)
                swap(a, i, j);
        }

        static void reverse(double[] a, int i, int j) {
            for (; i < j; i++, j--)
                swap(a, i, j);
        }

        static void reverse(char[] a, int i, int j) {
            for (; i < j; i++, j--)
                swap(a, i, j);
        }

        static void reverse(boolean[] a, int i, int j) {
            for (; i < j; i++, j--)
                swap(a, i, j);
        }

        static long sum(int[] a) {
            int sum = 0;
            for (int i : a)
                sum += i;
            return sum;
        }

        static long sum(long[] a) {
            long sum = 0;
            for (long i : a)
                sum += i;
            return sum;
        }

        static double sum(double[] a) {
            double sum = 0;
            for (double i : a)
                sum += i;
            return sum;
        }

        static int max(int[] a) {
            int max = Integer.MIN_VALUE;
            for (int i : a)
                if (i > max) max = i;
            return max;
        }

        static int min(int[] a) {
            int min = Integer.MAX_VALUE;
            for (int i : a)
                if (i < min) min = i;
            return min;
        }

        static long max(long[] a) {
            long max = Long.MIN_VALUE;
            for (long i : a)
                if (i > max) max = i;
            return max;
        }

        static long min(long[] a) {
            long min = Long.MAX_VALUE;
            for (long i : a)
                if (i < min) min = i;
            return min;
        }
    }
}
