#include<bits/stdc++.h>
using namespace std;
const int inf=200005;
int n,x;
vector<int>a[inf];
stack<int>s;
int low[inf],scc[inf],pre[inf],scc_cnt,scc_time,ans,mi=10000000;
inline void dfs(int x)
{
	low[x]=pre[x]=scc_time++;
	s.push(x);
	for(int i=0;i<a[x].size();i++)
	{
		int u=a[x][i];
		if(!pre[u])dfs(u),low[x]=min(low[x],low[u]);
		else if(!scc[u])low[x]=min(low[x],low[u]);
	}
	if(pre[x]==low[x])
	{
		int ans=0;
		scc_cnt++;
		for(;;)
		{
			int r=s.top();
			s.pop();
			scc[r]=scc_cnt;
			ans++;
			if(x==r)break;
		}
		if(ans>1)mi=min(mi,ans);
	}
}
int main()
{
	freopen("2015message.in","r",stdin);
	freopen("2015message.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
	{
		scanf("%d",&x);
		a[i].push_back(x);
	}
	for(int i=1;i<=n;i++)
	if(!pre[i])dfs(i);
//	for(int i=1;i<=n;i++)cout<<scc[i]<<" ";
	cout<<mi;
	return 0;
}