#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: BUDIN666
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/