#include <bits/stdc++.h>   using namespace std;   int a[10010];   int n, cnt;   int main() {     cin >> n;     for (int i = 1; i <= n; i++) cin >> a[i];     for (int i = 1; i <= n; i++)       if (a[a[i]] == i && a[i] <= i) cnt++;     cout << cnt << endl;     return 0;   }   