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

using namespace std;

int n,a[10001];
int t[10001];
int tn;
bool y[10001];

long long gcd(long long a,long long b)
{
	if (a<b) swap(a,b);
	if (b!=0) return gcd(b,a%b);
	return a;
}

int main()
{
	freopen("officer.in","r",stdin);
	freopen("officer.out","w",stdout);
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
	{
		scanf("%d",a+i);
	}
	
	for (int i=1;i<=n;i++)
	if (!y[i])
	{
		int now=i;int k=0;
		do
		{
			now=a[now];
			y[now]=true;
			k++;
		}while(now!=i);
		t[++tn]=k;
	}
	
	long long ans=t[1];
	
	for (int i=2;i<=tn;i++)
	{
		ans=(ans/gcd(ans,t[i]))*t[i];
	}
	
	printf("%lld\n",ans);
	
	return 0;
}