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

int main() {
	int n;
	cin >> n;
	vector<int> a(n + 1);
	for ( int i = 1; i <= n; i++ ) cin >> a[i];

	int cnt = 0;
	for ( int i = 1; i <= n; i++ ) {
		if ( a[a[i]] == i ) cnt++;
	}

	cout << cnt / 2 << endl;
}
