题目描述
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-----
5 2
5 3 1 4 2
1 3
5 4
-----Sample Output-----
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.
输入格式
见题面
输出格式
见题面