Submission #890710

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Source Code Expand

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<random>
#include<array>
#include<cassert>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())


int n, a[100000];

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	rep(i, n)cin >> a[i], a[i]--;
	int ans = 0;
	rep(i,n) {
		if (i == a[a[i]])ans++;
	}
	cout << ans / 2 << endl;
	return 0;
}

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