#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: lyy002
	Language: C++
	Result: Accepted
	Time:24 ms
	Memory:2072 kb
****************************************************************/