#include<stdio.h>
#include<math.h>
#include<bits/stdc++.h>
#include<iostream> 
using namespace std;
int main()
{
	int n,high;
	scanf("%d",&n);
	int a[n+1];
	int i,j;
	for(i=0;i<n;i++){
		a[i]=i;
	}
	for(int z=n,i=0;i<n;i++,z--){
		int k=1,x=1;
		for(j=2;j<=sqrt(a[i]);j++){
			if(a[i]%j==0){
				k=0; 
				break;
			}
		}
		for(j=2;j<=sqrt(a[z]);j++){
			if(a[z]%j==0){
				x=0; 
				break;
			}
		}
		if(x==1&&k==1&&a[i]!=1&&a[z]!=1&&a[i]*a[z]>high){
			high=a[i]*a[z];
		}
	}
	cout<<high;
	return 0;
}