#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;
	}   
}
/**************************************************************
	Problem: 1299
	User: huangsiyuan
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/