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.*;
  
public class Main {
	public static boolean[] visitedReds;
	public static boolean[] visitedBlues;
	
    static class FastScanner
    { 
        BufferedReader br; 
        StringTokenizer st; 
  
        public FastScanner() 
        { 
            br = new BufferedReader(new
                     InputStreamReader(System.in)); 
        } 
  
        String next() 
        { 
            while (st == null || !st.hasMoreElements()) 
            { 
                try
                { 
                    st = new StringTokenizer(br.readLine()); 
                } 
                catch (IOException  e) 
                { 
                    e.printStackTrace(); 
                } 
            } 
            return st.nextToken(); 
        } 
  
        int nextInt() 
        { 
            return Integer.parseInt(next()); 
        } 
  
        long nextLong() 
        { 
            return Long.parseLong(next()); 
        } 
  
        double nextDouble() 
        { 
            return Double.parseDouble(next()); 
        } 
  
        String nextLine() 
        { 
            String str = ""; 
            try
            { 
                str = br.readLine(); 
            } 
            catch (IOException e) 
            { 
                e.printStackTrace(); 
            } 
            return str; 
        } 
    } 
  
    public static void main(String[] args) throws IOException {
        FastScanner sc=new FastScanner();
        int N = sc.nextInt();
        Node[] nodes = new Node[N];
        for (int i = 0; i < N; i++) {
        	nodes[i] = new Node(i,sc.nextInt());
        }
        int[][] edges = new int[N-1][2];
        for (int i = 0; i < N-1; i++) {
        	int n1 = sc.nextInt()-1;
        	int n2 = sc.nextInt()-1;
        	nodes[n1].addChild(nodes[n2]);
        	nodes[n2].addChild(nodes[n1]);
        	edges[i][0] = n1;
        	edges[i][1] = n2;
        }
        visitedReds = new boolean[N];
        visitedBlues = new boolean[N];
        visitedReds[0] = true;
        visitedBlues[0] = true;
        //Recursion
        numReds(nodes[0]);
        numBlues(nodes[0]);
        int nice = 0;
        for (int[] edge: edges) {
        	Node node1 = nodes[edge[0]];
        	Node node2 = nodes[edge[1]];
        	if (node1.reds + node1.blues > node2.reds + node2.blues) {
        		//node2 is the subnode
        		if ((nodes[0].reds == node2.reds || nodes[0].blues == node2.blues) && (node2.reds == 0 || node2.blues == 0)) {
        			nice++;
        		}
        	} else {
        		//node1 is the subnode
        		if ((nodes[0].reds == node1.reds || nodes[0].blues == node1.blues) && (node1.reds == 0 || node1.blues == 0)) {
        			nice++;
        		}
        	}
        }
        System.out.println(nice);
    }
    
    public static int numReds(Node n) {
    	if (n.children.size() == 0) {
    		return n.reds;
    	} else {
    		int ans = n.reds;
    		for (Node child: n.children) {
    			if (visitedReds[child.n] == false) {
    				visitedReds[child.n] = true;
    				ans += numReds(child);
    			}
    		}
    		n.reds = ans;
    		return ans;
    	}
    }
    
    public static int numBlues(Node n) {
    	if (n.children.size() == 0) {
    		return n.blues;
    	} else {
    		int ans = n.blues;
    		for (Node child: n.children) {
    			if (visitedBlues[child.n] == false) {
    				visitedBlues[child.n] = true;
    				ans += numBlues(child);
    			}
    		}
    		n.blues = ans;
    		return ans;
    	}
    }
}

class Node {
	public int n;
	public ArrayList<Node> children;
	public int reds = 0;
	public int blues = 0;
	
	public Node(int n, int c) {
		this.n = n;
		if (c == 1) {
			reds = 1;
		} else if (c == 2) {
			blues = 1;
		}
		children = new ArrayList<Node>();
	}
	
	public void addChild(Node node) {
		children.add(node);
	}
}