#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: wangyousi
	Language: C++
	Result: Accepted
	Time:16 ms
	Memory:2072 kb
****************************************************************/