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

D=[[] for i in range(N)]
P=[-1]*N
for i in range(N):
  if A[i]!=0:
    D[i].append(A[i]-1)
    P[A[i]-1]=i

ans=0
V=[0]*N
for i in range(N):
  if P[i]==-1:
    for j in D[i]:
      for k in D[j]:
        V[k]=1
print(sum(V))