C# switch语句判断月份天数

            Console.WriteLine("请输入一个月份");
            int yue = int.Parse(Console.ReadLine());
            string tian;
            switch (yue)
            {
    
    
                case 1:
                case 3:
                case 5:
                case 7:
                case 8:
                case 10:
                case 12:
                    tian ="31天";
                    break;
                case 2:
                    tian = "28天";
                    break;
                case 4:
                case 6:
                case 9:
                case 11:
                    tian = "30天";
                    break;
                default:
                    tian = "月份输入有误";
                    break;
            }
            Console.WriteLine("{0}月有{1}。",yue,tian);
            Console.ReadKey();