题解 | #杨辉三角的变形#

import java.util.*;
public class Main{
    // 找规律
    // 奇数行:都为2
    // 偶数行:n/2结果为奇数,返回4,else 返回3
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        if(n == 1 || n == 2){
            System.out.println(-1);
        }else if(n % 2 != 0){
            System.out.println(2);
        }else{
            int x = n / 2;
            if(x % 2 == 0){
                System.out.println(3);
            }else{
                System.out.println(4);
            }
        }
    } 
}