#include<bits/stdc++.h>
using namespace std;

int main(){
  int n;
  cin>>n;
  vector<int> p(n+1);
  vector<vector<int>> g(n+1);
  vector<int> d(n+1);
  for (int i=1;i<=n;i++){
    cin>>p[i];
    d[p[i]]++;
    g[p[i]].push_back(i);
  }
  vector<bool> ok(n+1);
  for (int i=1;i<=n;i++){
    if (d[i]>0) continue;
    ok[p[p[i]]]=true;
  }
  int ans=0;
  for (int i=1;i<=n;i++) ans+=ok[i];
  cout<<ans<<endl;
}