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 Lua (LuaJIT 2.1.0) (judge verdict: Accepted)

local par={}
local size={}

local function init(n)
    for i=1,n do
        par[i]=i
        size[i]=1
    end
end

local function root(x)
    return par[x]==x and x or root(par[x])
end

local function same(x,y)
    return root(x)==root(y)
end

local function unite(x,y)
    x=root(x)
    y=root(y)
    if x==y then
        return
    end
    if size[x]>size[y] then
        x,y=y,x
    end
    par[x]=y
    size[y]=size[y]+size[x]
end

local function getsize(x)
    return size[root(x)]
end

----------

local n,m=io.read("n","n")
init(n)

local p={}
for i=1,n do
    p[i]=io.read("n")
end

for i=1,m do
    local x,y=io.read("n","n")
    unite(x,y)
end

local counter=0
for i=1,n do
    if same(p[i],i) then
        counter=counter+1
    end
end
print(counter)