#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: zhangchenhao
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/