putstr("Enter a month number: ");
var monthNum = readline(); // 要求数据类型是字符串？
var monthName;
switch (monthNum) {
  case "1":
    monthName = "January";
    print("January");
    break;
  case "2":
    monthName = "F";
    print(monthName);
    break;
  case "3":
    monthName = "M";
    print(monthName);
    break;
  case "4":
    monthName = "A";
    print(monthName);
    break;
  default:
    print("Bad input");
}