#include <bits/stdc++.h>
//#include <atcoder/modint>

using namespace std;
//using namespace atcoder;
using ll = long long;
//using mint = modint998244353;

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int N, ans=0;
    cin >> N;
    vector<vector<int>> E(N);
    vector<int> p(N);
    for (int i=0; i<N; i++){
        cin >> p[i];
        p[i]--;
        if (p[i] != -1){
            E[i].push_back(p[i]);
            E[p[i]].push_back(i);
        }
    }
    set<int> st;
    for (int i=0; i<N; i++){
        if (E[i].size() == 1 && p[i] != -1){ //式神を持っており、式神でない
            for (auto j : E[i]){
                if (st.count(j)) continue;
                ans += E[j].size()-1;
                st.insert(j);
            }
        }
    }
    cout << ans << endl;

    return 0;
}