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: Wrong Answer)

#入力関係
nm = list(map(int,input().split()))
N = nm[0]
M = nm[1]
p = list(map(int,input().split()))
xy = []
for i in range(M):
    xy_ = tuple(map(int,input().split()))
    xy.append(xy_)

#順列pのp[i]=iとなるiの数を数える関数
def count00():
    cnt00 = 0
    for i in range(N):
        if i+1==p[i]:
            cnt00+=1
    return cnt00

#順列pの場所を交換する関数
def swap(a,x,y):
    a[x],a[y] = a[y],a[x]

#操作をしてp[i]=iとなるiの数を数える関数
def count01():
    cnt01 = 0
    for j in range(N):
        if j+1==p[j]:
            cnt01+=1
    return cnt01

def judge():
    if cnt00<cnt01:
        return 1
    else:
        return 0

for i in range(M):
    cnt00 = count00()
    swap(p,xy[i][0]-1,xy[i][1]-1)
    cnt01 = count01()
    judge()
    if judge()==1:
        cnt00=cnt01
    elif judge()==0:
        break
print(cnt00)