n=int(input())
L=list(map(int,input().split()))

F=[1]*(n+1)
for i in range(n):
  if L[i]==0:
    F[i]=0
  else:
    F[L[i]-1]=0
  
cnt=[0]*n
for i in range(n):
  if F[i]:
    if L[L[i]-1]!=0:
      cnt[L[L[i]-1]-1]=1
print(sum(cnt))