#include<bits/stdc++.h>
using namespace std;
int main(){
	int x;
	cin>>x;
	if(x%2==0){
		cout<<"2"<<endl;
	}
	if(x%3==0){
		cout<<"3"<<endl;
	}	
	if(x%5==0){
		cout<<"5"<<endl;
	}
	if(x%7==0){
		cout<<"7"<<endl;
	}	
	return 0;
}

/**************************************************************
	Problem: 1299
	User: linyuhang
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/