#include <algorithm>
#include <cmath>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <stack>
#include <stdio.h>
#include <string>
#include <vector>
using namespace std;
typedef long long ll;

#define rep(i, init, end) for(ll i = init; i < end; i++)
#define REP(i, init, end) for(ll i = init; i < end + 1; i++)
#define rev(i, end, init) for(ll i = init - 1; i >= end; i--)
#define REV(i, end, init) for(ll i = init; i >= end; i--)
#define PI 3.14159265359
#define EPS 0.0000000001
// #define MOD 1000000007
//cout << std::fixed << std::setprecision(15) << y << endl;


int main(){
    ll N;
    cin >> N;

    ll A[N + 1];
    vector<ll> from[N + 1];
    rep(i, 1, N + 1){
        cin >> A[i];
        from[A[i]].push_back(i);
    }

    ll fromCount[N + 1];
    rep(i, 1, N + 1){
        fromCount[i] = from[i].size();
    }

    bool visited[N + 1];
    rep(i, 1, N + 1){
        visited[i] = false;
    }

    ll ans = 0;
    rep(i, 1, N + 1){
        if(!visited[i] && fromCount[i] > 0){
            stack<ll> st;
            st.push(i);
            ll p;
            while(!st.empty()){
                p = st.top();
                st.pop();
                if(visited[p]){
                    if(p == i){
                        ans++;//cout << "i: " << i << endl;
                    }
                    continue;
                }

                visited[p] = true;
                st.push(A[p]);
            }
        }
    }

    cout << ans << endl;

    return 0;
}