from collections import defaultdict

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

ps = [0] + P
freq = defaultdict(int)
for i in range(1, N+1):
    if ps[i] == 0: continue
    freq[ps[i]] += 1

ans = 0
for q in range(1, N+1):
    if freq[q] > 0: continue
    p = ps[q]
    if p == q: continue
    if p == 0: continue
    i = ps[p]
    if i > 0:
        ans += 1

print(ans)