import java.util.*;
class main{
    public static void main(String args[]){
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        if(n<=0){
            System.out.println("Invalid input");
        }else{
            for(int i=2;i<=n;i++){
                if(n%i==0){
                    System.out.println(i);
                    return;
                }
            }
            System.out.println(i);
        }
    }
}