修改上面的程序，在显示结果完成之后附加询问'Do you want to calculate again (y/n)，如果回答'y'，则要求重新输入参数，如果回答'n'，程序退出(Do while 循环)。

Modify the above program such that it will ask for 'Do you want to calculate again (y/n), if you say 'y', it'll again ask the parameters. If 'n', it'll exit.

youdao