#include<bits/stdc++.h>
using namespace std;
int main()
{
int n;
cin>>n;
if(n%2==0) cout<<2<<endl;
if(n%3==0) cout<<3<<endl;
if(n%5==0) cout<<5<<endl;
if(n%7==0) cout<<7<<endl;
return 0;
}
 
/**************************************************************
	Problem: 1299
	User: yangmata
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/