#include<bits/stdc++.h>
using namespace std;
int n,a[1000000];
int tong[1000000],s[10000000],cnt;
int minn=1e9;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		tong[a[i]]++;
		if(tong[a[i]]==2){
			cnt++;
			s[cnt]=a[i];
		}
	}
	for(int i=1;i<=cnt;i++){
		int t=s[i],ans=1;
		while(a[t]!=s[i]){
			ans++;
			t=a[t];
		}
		minn=min(ans,minn);
	}
	cout<<minn;
	return 0;
}