#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;
    }
     
}
/**************************************************************
	Problem: 1299
	User: chenjiahui
	Language: C
	Result: Compile Error
****************************************************************/