Problem: You are given an undirected tree of n vertices. 

Some vertices are colored blue, some are colored red and some are uncolored. It is guaranteed that the tree contains at least one red vertex and at least one blue vertex.

You choose an edge and remove it from the tree. Tree falls apart into two connected components. Let's call an edge nice if neither of the resulting components contain vertices of both red and blue colors.

How many nice edges are there in the given tree?

Input

The first line contains a single integer n (2 ≤ n ≤ 3 ⋅ 10^5) — the number of vertices in the tree.

The second line contains n integers a_1, a_2, ..., a_n (0 ≤ a_i ≤ 2) — the colors of the vertices. a_i = 1 means that vertex i is colored red, a_i = 2 means that vertex i is colored blue and a_i = 0 means that vertex i is uncolored.

The i-th of the next n - 1 lines contains two integers v_i and u_i (1 ≤ v_i, u_i ≤ n, v_i ≠ u_i) — the edges of the tree. It is guaranteed that the given edges form a tree. It is guaranteed that the tree contains at least one red vertex and at least one blue vertex.

Output

Print a single integer — the number of nice edges in the given tree.

Examples

Input


5
2 0 0 1 2
1 2
2 3
2 4
2 5


Output


1


Input


5
1 0 0 0 2
1 2
2 3
3 4
4 5


Output


4


Input


3
1 1 2
2 3
1 3


Output


0

Note

Here is the tree from the first example:

<image>

The only nice edge is edge (2, 4). Removing it makes the tree fall apart into components \{4\} and \{1, 2, 3, 5\}. The first component only includes a red vertex and the second component includes blue vertices and uncolored vertices.

Here is the tree from the second example:

<image>

Every edge is nice in it.

Here is the tree from the third example:

<image>

Edge (1, 3) splits the into components \{1\} and \{3, 2\}, the latter one includes both red and blue vertex, thus the edge isn't nice. Edge (2, 3) splits the into components \{1, 3\} and \{2\}, the former one includes both red and blue vertex, thus the edge also isn't nice. So the answer is 0.

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;
import java.lang.*;


public class Main implements Runnable {
    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        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 String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }

        public int nextInt() {
            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 long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long 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 double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

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

            return res.toString();
        }

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

        public String next() {
            return readString();
        }

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

    public static void main(String args[]) throws Exception {
        new Thread(null, new Main(), "Main", 1 << 26).start();
    }

    static long gcd(long a, long b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    static int gcd(int a, int b) {
        if (b == 0) return a;
        return gcd(b, a % b);
    }

    static long modPow(long a, long p, long m) {
        if (a == 1) return 1;
        long ans = 1;
        while (p > 0) {
            if (p % 2 == 1) ans = (ans * a) % m;
            a = (a * a) % m;
            p >>= 1;
        }
        return ans;
    }

    static long modInv(long a, long m) {
        return modPow(a, m - 2, m);
    }

    static long sol_x, sol_y, gcd_a_b;

    static void extendedEuclid(long a, long b) {
        if (b == 0) {
            gcd_a_b = a;
            sol_x = 1;
            sol_y = 0;
        } else {
            extendedEuclid(b, a % b);
            long temp = sol_x;
            sol_x = sol_y;
            sol_y = temp - (a / b) * sol_y;
        }
    }

    long modInverse(long a, long prime)
    {
        a = a % prime;
        for (int x=1; x<prime; x++)
            if ((a*x) % prime == 1)
                return x;

        return -1;
    }

    static class Bhavansort {
        Random random;

        Bhavansort(int a[]) {
            randomArray(a);
            sort(a);
        }

        Bhavansort(long a[]) {
            randomArray(a);
            sort(a);
        }

        static int[] sort(int a[]) {
            Arrays.sort(a);
            return a;
        }

        static long[] sort(long a[]) {
            Arrays.sort(a);
            return a;
        }

        void randomArray(long a[]) {
            int n = a.length;
            for (int i = 0; i < n; i++) {
                int p = random.nextInt(n) % n;
                long tm = a[i];
                a[i] = a[p];
                a[p] = tm;
            }
        }

        void randomArray(int a[]) {
            int n = a.length;
            for (int i = 0; i < n; i++) {
                int p = random.nextInt(n) % n;
                int tm = a[i];
                a[i] = a[p];
                a[p] = tm;
            }
        }
    }

    void dfs(int u,int par,ArrayList<Integer> l[],int a[]){
        if(a[u]==1)countRed[u]++;
        if(a[u]==2)countBlue[u]++;
        for(int v:l[u]){
            if(v==par)continue;
            dfs(v,u,l,a);
            countRed[u]+=countRed[v];
            countBlue[u]+=countBlue[v];
        }
    }

    int countRed[],countBlue[];


    public void run() {
        InputReader sc = new InputReader(System.in);
        //Scanner sc=new Scanner(System.in);
        // Random rn=new Random();
        PrintWriter out = new PrintWriter(System.out);

        int n=sc.nextInt()+1;
        int a[]=new int[n];
        int red=0,blue=0;
        for (int i = 1; i <n ; i++) {
            a[i]=sc.nextInt();
            if(a[i]==1)red++;
            if(a[i]==2)blue++;
        }
        ArrayList<Integer> l[]=new ArrayList[n];
        for(int i=0;i<n;i++)l[i]=new ArrayList<>();
        for (int i = 0; i <n-2 ; i++) {
            int u=sc.nextInt();
            int v=sc.nextInt();
            l[u].add(v);
            l[v].add(u);
        }
        countBlue=new int[n];
        countRed=new int[n];

        dfs(1,0,l,a);

        int ans=0;
        for (int i = 1; i <n ; i++) {
            if(countRed[i]==red && countBlue[i]==0)ans++;
            if(countBlue[i]==blue && countRed[i]==0)ans++;
        }
        out.println(ans);



        out.close();

    }


}