#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);++i)
signed main(){
  cin.tie(0)->sync_with_stdio(0);
  int N;cin>>N;
  vector<int>P(N),inv(N,-1);
  rep(i,N){
    cin>>P[i];
    --P[i];
    if(P[i]!=-1)inv[P[i]]=i;
  }
  int ans=0;
  vector<bool>fl(N);
  rep(i,N){
    if(P[i]!=-1&&inv[i]!=-1){
      if(!fl[P[i]])++ans;
      fl[P[i]]=1;
    }
  }
  cout<<ans<<endl;
}