N=int(input())
P=list(map(int,input().split()))
for i in range(N):
  P[i]-=1
A=P[:]
v=[0]*N
for i in range(N):
  x=A[i]
  if x>=0:
    v[x]+=1
result=[0]*N
for i in range(N):
  if v[i]==0:
    pos=P[i]
    if pos>=0:
      a=P[pos]
      if a>=0:
        result[a]=1
print(sum(result))