救

#include<bits/stdc++.h>
using namespace std;
map <int,int> dat;
int father[200011];
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		int temp;
		cin>>temp;
		dat[i]=temp;
		father[i]=i;
	}
	int ans=0;
	bool pd=0;
	while(!pd)
	{
		ans++;
		for(int i=1;i<=n;i++)
		{
			father[i]=dat[father[i]];
			if(father[i]==i)
			{
				cout<<ans;
				return 0;
			}
		}
	}
	return 0;
}