import sys
input = sys.stdin.readline

n=int(input())
A=list(map(int,input().split()))

# UnionFind

Group = [i for i in range(n+1)] # グループ分け
Nodes = [1]*(n+1) # 各グループのノードの数

def find(x):
    while Group[x] != x:
        x=Group[x]
    return x

def Union(x,y):
    if find(x) != find(y):
        if Nodes[find(x)] < Nodes[find(y)]:
            
            Nodes[find(y)] += Nodes[find(x)]
            Nodes[find(x)] = 0
            Group[find(x)] = find(y)
            
        else:
            Nodes[find(x)] += Nodes[find(y)]
            Nodes[find(y)] = 0
            Group[find(y)] = find(x)

for i in range(n):
    Union(i,A[i]-1)

ANS=0
for i in range(n):
    if find(i)==i:
        ANS+=1

print(ANS)