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

pair<vector<int>,vector<vector<int>>> FunctionalGraph(const vector<int> &A){
    //N頂点N辺有向出次数全て1のグラフでreturn{cycle所属番号(-1は未所属),cycle頂点集合}.
    int N = A.size(),nowc = 0;
    vector<int> belong(N,-1);
    vector<vector<int>> cycle;
    vector<bool> already(N),visited(N);
    for(int i=0; i<N; i++){
        if(already.at(i)) continue;
        int pos = i;
        bool check = true;
        while(!visited.at(pos)) visited.at(pos) = true,pos = A.at(pos);
        if(already.at(pos)) check = false;
        int memo = pos;
        pos = i;
        while(!already.at(pos)) already.at(pos) = true,pos = A.at(pos);
        if(!check) continue;
 
        pos = memo;
        vector<int> now = {pos};
        belong.at(pos) = nowc; pos = A.at(pos);
        while(pos != memo) now.push_back(pos),belong.at(pos) = nowc,pos = A.at(pos);
        cycle.emplace_back(now),nowc++;
    }
    return {belong,cycle};
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
 
    int N; cin >> N;
    vector<int> A(N);
    for(auto &a : A) cin >> a,a--;
    auto [belong,cycle] = FunctionalGraph(A);
    int answer = 0;
    for(auto &c : cycle) answer++;
    cout << answer << endl;
}