#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,s;
	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: chenyaohuo
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/