#include<bits/stdc++.h>
using namespace std;
int n;
int a[200010];
int whead[200010],wnext[200010],ver[200010];
int tot;
int mp[200010];
int ans=1e9;
void add(int x,int y)
{
	ver[++tot]=y;
	wnext[tot]=whead[x];
	whead[x]=tot;
	return;
}
void f(int x,int cs)
{
	if(mp[x])
	{
		ans=ans<cs?ans:cs;
		return;
	}
	mp[x]=1;
	for(int i=whead[x];i;i=wnext[i])
	{
		int y=ver[i];
		f(y,cs+1);
	}
	mp[x]=0;
	return;
}
int main()
{
	cin>>n;
	for(int i=1;i<=n;++i)
	{
		cin>>a[i];
		add(i,a[i]);
	}
	for(int i=1;i<=n;++i)
	{
		f(i,0);
	}
	cout<<ans;
	return 0;
}