Submission #891060

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Source Code Expand

#include <bits/stdc++.h>
#define rep(i, a, n) for(int i = a; i < n; i++)
#define repb(i, a, b) for(int i = a; i >= b; i--)
#define all(a) a.begin(), a.end()
#define int long long
using namespace std;
typedef pair<int, int> P;

signed main(){
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, 0, n){
        cin >> a[i];
        a[i]--;
    }
    int ans = 0;
    rep(i, 0, n){
        int id = a[i];
        if(a[id] == i) ans++;
    }
    cout << ans / 2 << endl;
}

Submission Info

Judge Result