Submission #891633

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define vvi vector< vector<int> >
#define vi vector<int>
#define All(X) X.begin(),X.end()
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define pb push_back
#define pii pair<int,int>
#define mp make_pair
#define pi 3.14159265359
#define shosu(X) fixed << setprecision(X)
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}
int a[100001];
int main(){
	int n;
	cin >> n;
	REP(i,n) cin >> a[i];
	int cnt = 0;
	REP(i,n){
		if(a[a[i]-1] == i+1) cnt++;
	} 
	cout << cnt/2 << endl;
}

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