N = int(input())
P = list(map(int,input().split()))
for i in range(N):
    P[i] -= 1

a = [0] * N

pset = set(P)

for q in range(N):
    if q not in pset:
        p = P[q]
        if p != -1 and P[p] != -1:
            a[P[p]] = 1

# print (*a)
print (sum(a))