#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	if(n%2==0) cout<<2;
	if(n%3==0) cout<<3;
	if(n%5==0) cout<<5;
	if(n%7==0) cout<<7;
}
/**************************************************************
	Problem: 1299
	User: lijinkai
	Language: C++
	Result: Wrong Answer
****************************************************************/