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.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.*;
import java.util.*;
import java.util.LinkedList;
import java.math.*;
import java.lang.*;
import java.util.PriorityQueue;
import static java.lang.Math.*;
@SuppressWarnings("unchecked")
public class Solution 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);
        }
    }
    static class triple
    {
      int red;
      int blue;
      int uncol;
      triple(int red,int blue,int uncol)
      {
        this.red = red;
        this.blue = blue;
        this.uncol = uncol;
      }
    }
    public static long min(long a,long b)
    {
        if(a>b)
        {
            return b;
        }
        return a;
    }
    public static int min(int a,int b)
    {
        if(a>b)
        {
            return b;
        }
        return a;
    }
    public static long max(long a,long b)
    {
        if(a>b)
        {
            return a;
        }
        return b;
    }
    public static int max(int a,int b)
    {
        if(a>b)
        {
            return a;
        }
        return b;
    }
    static class pair
    {
      int x;
      int y;
      pair(int x,int y)
      {
        this.x = x;
        this.y = y;
      }
    }
    public static int gcd(int a,int b)
    {
        if(a==0)
        return b;
        if(b==0)
        return a;
        while((a%=b)!=0&&(b%=a)!=0);
        return a^b;
    }
    public static void tadd(triple t1,triple t2)
    {
      t1.red+=t2.red;
      t1.blue+=t2.blue;
      t1.uncol+=t2.uncol;
    }
    static int num = (int)1e6;
    static ArrayList<Integer>[] list;
    static int[] a;
    static int[] count;
    static int ans = 0;
    public static triple dfs(int u,int p)
    {
      triple t = new triple(0,0,0);
      for(Integer v:list[u])
      {
        if(v!=p)
        {
          triple c = dfs(v,u);
          if(c.red==count[1] && c.blue==0)
          {
            ans++;
          }
          else if(c.blue==count[2]&&c.red==0)
          {
            ans++;
          }
          tadd(t,c);
        }
      }
      if(a[u]==0)
      {
        t.uncol++;
      }
      else if(a[u]==1)
      {
        t.red++;
      }
      else
      {
        t.blue++;
      }
      return t;
    }
    public static int random(int min,int max)
    {
      return min+(int)((max-min)*Math.random());
    }
    public static void main(String args[]) throws Exception {
        new Thread(null, new Solution(),"Main",1<<26).start();
    }    public void run() {
      InputReader sc  = new InputReader(System.in);
      PrintWriter out = new PrintWriter(System.out);
      int t1 = 1;
      while(t1-->0)
      {
        int n = sc.nextInt();
        list = new ArrayList[n];
        for(int i=0;i<n;i++)
        {
          list[i] = new ArrayList<>();
        }
        a = new int[n];
        count = new int[3];
        for(int i=0;i<n;i++)
        {
          a[i] = sc.nextInt();
          count[a[i]]++;
        }
        for(int i=0;i<n-1;i++)
        {
          int x = sc.nextInt()-1;
          int y = sc.nextInt()-1;
          list[x].add(y);
          list[y].add(x);
        }
        dfs(0,-1);
        out.println(ans);
      }
      out.close();
  }
}