题解 | #杨辉三角的变形#--找规律

import java.util.Scanner;

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