题解 | #杨辉三角的变形#，跟着大佬找规律

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {
            int n = in.nextInt();
            if (n < 3){
                System.out.println("-1");
            }else {
                int i = n % 4;
                switch (i){
                    case 0 :
                        System.out.println("3");
                        break;
                    case 2 :
                        System.out.println("4");
                        break;
                    default:
                        System.out.println("2");
                        break;
                }
            }
        }
    }
}