Problem:
Score : 400 points

Problem Statement

We have a permutation of the integers from 1 through N, p_1, p_2, .., p_N.
We also have M pairs of two integers between 1 and N (inclusive), represented as (x_1,y_1), (x_2,y_2), .., (x_M,y_M).
AtCoDeer the deer is going to perform the following operation on p as many times as desired so that the number of i (1 ≤ i ≤ N) such that p_i = i is maximized:

Choose j such that 1 ≤ j ≤ M, and swap p_{x_j} and p_{y_j}.

Find the maximum possible number of i such that p_i = i after operations.

Constraints

2 ≤ N ≤ 10^5

1 ≤ M ≤ 10^5

p is a permutation of integers from 1 through N.

1 ≤ x_j,y_j ≤ N

x_j ≠ y_j

If i ≠ j, \{x_i,y_i\} ≠ \{x_j,y_j\}.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
p_1 p_2 .. p_N
x_1 y_1
x_2 y_2
:
x_M y_M

Output

Print the maximum possible number of i such that p_i = i after operations.

Sample Input 1

5 2
5 3 1 4 2
1 3
5 4

Sample Output 1

2

If we perform the operation by choosing j=1, p becomes 1 3 5 4 2, which is optimal, so the answer is 2.

Sample Input 2

3 2
3 2 1
1 2
2 3

Sample Output 2

3

If we perform the operation by, for example, choosing j=1, j=2, j=1 in this order, p becomes 1 2 3, which is obviously optimal.
Note that we may choose the same j any number of times.

Sample Input 3

10 8
5 3 6 8 7 10 9 1 2 4
3 1
4 1
5 9
2 5
6 5
3 5
8 9
7 9

Sample Output 3

8

Sample Input 4

5 1
1 2 3 4 5
1 5

Sample Output 4

5

We do not have to perform the operation.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)


import java.util.Scanner;

public class Main {

	public static int[] tree;
	public static int[] dep;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();
		int[] p = new int[n];
		tree = new int[n];
		dep = new int[n];
		for(int i = 0; i < n; i++) {
			p[i] = sc.nextInt() - 1;
			tree[i] = i;
			dep[i] = 0;
		}
		for(int i = 0; i < m; i++) {
			union(sc.nextInt() - 1, sc.nextInt() - 1);
		}
		int ans = 0;
		for(int i = 0; i < n; i++) {
			if(root(p[i]) == root(i)) {
				ans++;
			}
		}
		System.out.println(ans);
	}

	public static int root(int i) {
		if(tree[i] == i) {
			return i;
		} else {
			return root(tree[i]);
		}
	}

	public static void union(int i, int j) {
		int iroot = root(i);
		int jroot = root(j);
		if(dep[iroot] <= dep[jroot]) {
			tree[iroot] = jroot;
			dep[jroot]++;
		} else {
			tree[jroot] = iroot;
			dep[iroot]++;
		}
	}

}