#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	cin>>a;
	if(a%2==0) cout<<"2"<<endl;
	if(a%3==0) cout<<"3"<<endl;
	if(a%5==0) cout<<"5"<<endl;
	if(a%7==0) cout<<"7";
}
/**************************************************************
	Problem: 1299
	User: sucongyi
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/