#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;
	 
}
/**************************************************************
	Problem: 1299
	User: wngjinming
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/