#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: hbq
	Language: C++
	Result: Compile Error
****************************************************************/