N = int(input())
oya = [-1] * N
P = list(map(int, input().split()))

for i in range(N):
	P[i] -= 1
	oya[P[i]] = i

ans = 0
ok = [False] * N
for i in range(N):
	if oya[i] != -1 and oya[oya[i]] == -1:
		if P[i] != -1:
			ok[P[i]] = True
print(sum(ok))