#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: linmiaoling
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/