#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: linzihang
	Language: C++
	Result: Compile Error
****************************************************************/