#include<bits/stdc++.h>
using namespace std;
int n;
int main(){
	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: zhangziang
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/