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

S = [0] * N

ans = 0
for i in range(N):
    now_idx = i
    now_li = []
    if not S[now_idx]:
        while not S[now_idx]:
            now_li.append(now_idx)
            S[now_idx] = 1
            now_idx = A[now_idx] - 1 # 1-indexed を 0-indexedに直す
        if S[now_idx] == 1:
            ans += 1
    for idx in now_li:
        S[idx] = 2

print(ans)