Submission #895454

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
#define pb push_back
#define mp make_pair
#define fi first
#define se second

int main()
{
	int n,a,sum=0;
	vi v;
	set<int>S;
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>a;
		v.pb(a);
	}
	for(int i=0;i<n;i++)	
	{
		if(i==v[v[i]-1]-1&&S.find(i)==S.end()&&S.find(v[i]-1)==S.end())
		{
			sum++;
			S.insert(i);
			S.insert(v[i]-1);
		}
	}
	cout<<sum<<endl;
	return 0;
}

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