#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>

using namespace std;

int n,i,j,k,sum[10001],tot=0,num[10001],a[10001],ci,MAX;
bool b[10001];
long long ans=1;

void init()
{
	freopen("officer.in","r",stdin);
	freopen("officer.out","w",stdout);
	scanf("%d",&n);
	for (i=1;i<=n;i++)
	{
		scanf("%d",a+i);
	}
}

void solve()
{
	memset(b,false,sizeof(b));
	for (i=2;i<=10000;i++)
		if (!b[i])
		{
			j=i;
			sum[++tot]=i;
			num[tot]=1;
			while (j<=10000)
			{
				b[j]=true;
				j+=i;
			}
		}
	for (i=1;i<=n;i++)
	{
		j=i;
		ci=0;
		do
		{
			j=a[j];
			ci++;
		}
		while (j!=i);
		for (j=1;j<=tot;j++)
		{
			MAX=1;
			while (ci%sum[j]==0)
			{
				ci=ci/sum[j];
				MAX*=sum[j];
			}
			num[j]=max(num[j],MAX);
		}
	}
	for (i=1;i<=tot;i++)
		ans*=num[i];
	cout<<ans<<endl;
}

int main()
{
	init();
	solve();
	return 0;
}