程序代码：

main()
{
    int fs;
    scanf("fs",&fs);
    switch (fs)
    {
      case 0 :printf("a");break;
      case 1 :printf("b");break;
      case 2 :printf("c");break;
      case 3 :printf("d");break;
      case 4 :printf("e");break;
      case 5 :printf("f");break;
      case 6 :printf("g");break;
      case 7 :printf("h");break;
      case 8 :printf("i");break;
      case 9 :printf("j");break;
      case 10:printf("k");break;
      default :printf("xxx");
     }
   getch();
}