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 Python (3.4.3) (judge verdict: Accepted)

from collections import deque
N,M = map(int,input().split())
p = [0] + list(map(int,input().split()))
l = [[] for _ in range(N+1)]
for i in range(M):
  x,y = map(int,input().split())
  l[x].append(y)
  l[y].append(x)

#unionfind
lp = [i for i in range(N+1)] #親のリスト
#木の根を求める
def root(x):
  if lp[x] == x:
    return x
  else:
    lp[x] = root(lp[x])
    return lp[x]
#xとyが同じ集合に属するか否か
def det(x,y):
  return root(x) == root(y)
#xとYが属する集合の併合 Yが親になる
def unite(x,y):
  x = root(x)
  y = root(y)
  if x != y:
    lp[x] = y 

seen = [False]*(N+1)
for i in range(1,N+1):
  if seen[i] == False:
    seen[i] = True
    d = deque([i])
    while len(d)>0:
      v = d.popleft()
      for j in l[v]:
        if seen[j] == False:
          seen[j] = True
          unite(j,i)
          d.append(j)
###
cnt = 0
for i in range(1,N+1):
  cnt += int(det(p[i],i))
print(cnt)