#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: mc002
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/