Submission #890828

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Source Code Expand

#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
const ld eps = 1e-9;

//// < "d:\d_download\visual studio 2015\projects\programing_contest_c++\debug\a.txt" > "d:\d_download\visual studio 2015\projects\programing_contest_c++\debug\b.txt"


int main() {
	/*string st; cin >> st;
	for (int i = 0; i < 4; ++i) {
		cout << st[i];
	}
	cout << " ";
	for (int i = 4; i < 12; ++i) {
		cout << st[i];
	}
	cout << endl;
*/
	int N; cin >> N;
	int ans = 0;
	vector<int>vs(N);
	for (int i = 0; i < N; ++i) {
		cin >> vs[i];
		vs[i]--;
	}
	for (int i = 0; i < N; ++i) {
		if (vs[vs[i]] == i)ans++;
	}
	cout << ans / 2 << endl;
	return 0;
}

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