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

int main() { 
  int n, ans = 0;
  cin >> n;
  int a[n+1];
  for(int i = 1; i <= n; ++i) cin >> a[i];
  for(int i = 1; i <= n; ++i) {
    if(a[a[i]] == i) ans++;
  }
  cout << ans/2 << '\n'; 
}
