import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
            int n=sc.nextInt();
            if(n==1 || n==2){
                System.out.println(-1);
            }
            else if(n%4==3 || n%4==1){
                System.out.println(2);
            }
             else if(n%4==0){
                 System.out.println(3);
            }
             else if(n%4==2){
                 System.out.println(4);
            }
        }
    }
}