The Bovine Shuffle

#include <bits/stdc++.h>

using namespace std;

int n;
vector<int> np;
vector<bool> visited;
vector<bool> cycle;
int og;
int ans;

void dfs(int node){
    if(visited[node]) return;
    visited[node] = true;
    if(np[node] == og){
        cycle[og] = true;
        int v = np[og];
        while(v!=og){
            cycle[v] = true;
            v = np[v];
        }
        return;
    }
    if(!visited[np[node]]){
        dfs(np[node]);
    }
}

int main(){
    //freopen("bshuffle.in", "r", stdin);

    cin >> n;
    np.resize(n+1);
    visited.resize(n+1, false);
    cycle.resize(n+1, false);
    for(int i=1; i<=n; i++){
        int v;
        cin >> v;
        np[i] = v;
    }
    for(int i=1; i<=n; i++){
        //visited.clear();
        fill(visited.begin(), visited.end(), false);
        //cout << visited[i] << '\n';
        og = i;
        if(!cycle[i]){
            //cout << "HI" << " || " << i << '\n';
            dfs(i);
        }
        if(cycle[i]){
            //cout << "i: " << i << '\n';
            ans++;
        }
    }
    cout << ans << '\n';

    return 0;
}