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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;

public class P1118F1
{
	private static int n;
	private static int[] a, b, colour;
	private static int[][] branchColours;
	private static Point[] points;
	private static ArrayList<Integer> interactivePoints;
	
	private static class Point
	{
		private ArrayList<Integer> edges;
		private Object possibleBranchColour;
		private Object possiblePosition;
		
		private Point()
		{
			edges = new ArrayList<Integer>();
			this.possibleBranchColour = this.possiblePosition = null;
		}
	}
	
	private static int dfs(int cutEdge, int aOrB)
	{
		if (branchColours[aOrB][cutEdge] != -2)
		{
			return branchColours[aOrB][cutEdge];
		}
		int currentPosition = aOrB == 0 ? a[cutEdge] : b[cutEdge];
		Point currentPoint = points[currentPosition];
		int branchColour = colour[currentPosition];
		for (int i : currentPoint.edges)
		{
			if (i != cutEdge)
			{
				int subBranch = a[i] == currentPosition ? dfs(i, 1) : dfs(i, 0);
				if (branchColour == 0)
				{
					branchColour = subBranch;
					if (branchColour == -1)
					{
						break;
					}
				}
				else if (branchColour == 1)
				{
					if (subBranch == -1 || subBranch == 2)
					{
						branchColour = -1;
						break;
					}
				}
				else if (branchColour == 2)
				{
					if (subBranch == -1 || subBranch == 1)
					{
						branchColour = -1;
						break;
					}
				}
				else
				{
					throw new AssertionError();
				}
			}
		}
		branchColours[aOrB][cutEdge] = branchColour;
		return branchColour;
	}
	
	private static void interactivePointSetUp(int position)
	{
		Point currentPoint = points[position];
		int redCounter = 0, blueCounter = 0, mixCounter = 0, redPosition = -1, bluePosition = -1, mixPosition = -1;
		if (colour[position] == 1)
		{
			redCounter += 2;
		}
		else if (colour[position] == 2)
		{
			blueCounter += 2;
		}
		for (int i : currentPoint.edges)
		{
			int branch = a[i] == position ? dfs(i, 1) : dfs(i, 0);
			if (branch == -1)
			{
				mixCounter++;
				mixPosition = i;
			}
			else if (branch == 1)
			{
				redCounter++;
				redPosition = i;
			}
			else if (branch == 2)
			{
				blueCounter++;
				bluePosition = i;
			}
		}
		if (mixCounter > 1)
		{
			currentPoint.possibleBranchColour = -1;
		}
		else if (mixCounter == 1)
		{
			if (redCounter > 0 && blueCounter > 0)
			{
				currentPoint.possibleBranchColour = -1;
			}
			else if (redCounter > 0)
			{
				currentPoint.possibleBranchColour = new int[] {1};
				currentPoint.possiblePosition = new int[] {mixPosition};
			}
			else if (blueCounter > 0)
			{
				currentPoint.possibleBranchColour = new int[]{2};
				currentPoint.possiblePosition = new int[] {mixPosition};
			}
			else
			{
				currentPoint.possibleBranchColour = new int[] {0};
				currentPoint.possiblePosition = new int[] {mixPosition};
			}
		}
		else
		{
			if (redCounter > 1 && blueCounter > 1)
			{
				currentPoint.possibleBranchColour = -1;
			}
			else if (redCounter == 1 && blueCounter > 1)
			{
				currentPoint.possibleBranchColour = new int[] {2};
				currentPoint.possiblePosition = new int[] {redPosition};
			}
			else if (redCounter > 1 && blueCounter == 1)
			{
				currentPoint.possibleBranchColour = new int[] {1};
				currentPoint.possiblePosition = new int[] {bluePosition};
			}
			else if (redCounter == 1 && blueCounter == 1)
			{
				currentPoint.possibleBranchColour = new int[] {1, 2};
				currentPoint.possiblePosition = new int[] {bluePosition, redPosition};
			}
			else if (redCounter > 1 && blueCounter == 0)
			{
				currentPoint.possibleBranchColour = new int[] {1};
				currentPoint.possiblePosition = new int[] {-n};
			}
			else if (redCounter == 0 && blueCounter > 1)
			{
				currentPoint.possibleBranchColour = new int[] {2};
				currentPoint.possiblePosition = new int[] {-n};
			}
			else if (redCounter == 0 && blueCounter == 1)
			{
				currentPoint.possibleBranchColour = new int[] {0, 2};
				currentPoint.possiblePosition = new int[] {bluePosition, - n};
			}
			else if (redCounter == 1 && blueCounter == 0)
			{
				currentPoint.possibleBranchColour = new int[] {0, 1};
				currentPoint.possiblePosition = new int[] {redPosition, - n};
			}
			else
			{
				currentPoint.possibleBranchColour = new int[] {0};
				currentPoint.possiblePosition = new int[] {-n};
			}
		}
	}
	
	private static int modifiedDfs(int cutEdge, int aOrB)
	{
		if (branchColours[aOrB][cutEdge] != -2)
		{
			return branchColours[aOrB][cutEdge];
		}
		int currentPosition = aOrB == 0 ? a[cutEdge] : b[cutEdge];
		Point currentPoint = points[currentPosition];
		int branchColour;
		if (!interactivePoints.contains(currentPosition))
		{
			return dfs(cutEdge, aOrB);
		}
		else
		{
			if (currentPoint.possibleBranchColour instanceof Integer)
			{
				branchColour = -1;
			}
			else
			{
				int[] possibleColours = (int[]) currentPoint.possibleBranchColour;
				int[] possiblePositions = (int[]) currentPoint.possiblePosition;
				if (possibleColours.length == 1)
				{
					if (possiblePositions[0] > 0)
					{
						if (cutEdge != possiblePositions[0])
						{
							branchColour = -1;
						}
						else
						{
							branchColour = possibleColours[0];
						}
					}
					else
					{
						branchColour = possibleColours[0];
					}
				}
				else if (possibleColours.length == 2)
				{
					if (possiblePositions[1] > 0)
					{
						if (cutEdge == possiblePositions[0])
						{
							branchColour = possibleColours[0];
						}
						else if (cutEdge == possiblePositions[1])
						{
							branchColour = possibleColours[1];
						}
						else
						{
							branchColour = -1;
						}
					}
					else
					{
						if (cutEdge == possiblePositions[0])
						{
							branchColour = possibleColours[0];
						}
						else
						{
							branchColour = possibleColours[1];
						}
					}
				}
				else
				{
					throw new AssertionError();
				}
			}
		}
		branchColours[aOrB][cutEdge] = branchColour;
		return branchColour;
	}
	
	public static void main(String [ ] args) throws IOException
	{
		BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
		n = Integer.parseInt(input.readLine());
		String colourLine = input.readLine();
		String[] colourArray = colourLine.split(" ");
		colour = new int[n];
		a = new int[n - 1];
		b = new int[n - 1];
		points = new Point[n];
		interactivePoints = new ArrayList<Integer>();
		for (int i = 0; i < n; i++)
		{
			colour[i] = Integer.parseInt(colourArray[i]);
			points[i] = new Point();
		}
		for (int i = 0; i < n - 1; i++)
		{
			String edgeLine = input.readLine();
			String[] edgeVertex = edgeLine.split(" ");
			a[i] = Integer.parseInt(edgeVertex[0]) - 1;
			b[i] = Integer.parseInt(edgeVertex[1]) - 1;
			points[a[i]].edges.add(i);
			points[b[i]].edges.add(i);
		}
		input.close();
		int niceEdges = 0;
		branchColours = new int[2][n - 1];
		for (int i = 0; i < n - 1; i++)
		{
			branchColours[0][i] = branchColours[1][i] = -2;
		}
		for (int i = 0; i < n; i++)
		{
			if (points[i].edges.size() > 2 * Math.sqrt(n))
			{
				interactivePoints.add(i);
				interactivePointSetUp(i);
			}
		}
		for (int i = 0; i < n - 1; i++)
		{
			if (modifiedDfs(i, 0) != -1 && modifiedDfs(i, 1) != -1)
			{
				niceEdges++;
			}
		}
		System.out.print(niceEdges);
	}
}