#include <bits/stdc++.h>
using namespace std;
#if __has_include("all.hpp")
#include "all.hpp"
#else
#include <atcoder/all>
#endif
using namespace atcoder;
int main(void){
    int n;
    cin>>n;
    dsu d(n);
    for(int i=0;i<n;i++){
        int a;
        cin>>a;
        d.merge(a-1,i);
    }
    vector<vector<int>>g=d.groups();
    cout<<g.size()<<endl;
    return 0;
}