n = int(input())
A = list(map(lambda x: int(x)-1, input().split()))
node = [[] for _ in range(n)]
for u in range(n):
    node[u].append(A[u])
    node[A[u]].append(u)

ans = 0
X = [1] * n
for s in range(n):
    if not X[s]: continue
    S = [s]
    X[s] = 0
    ans += 1
    while S:
        u = S.pop()
        for v in node[u]:
            if X[v]:
                X[v] = 0
                S.append(v)
print(ans)