本程序需在DOS下运行。每运行一次可执行程序random.exe，即可显示任意两个

16进制数的加法或减法表达式及其运算结果。在减法运算中，如果被减数小于减数，显示

“Divide Overflow”的提示信息。-The process required to run under DOS. Each time you run the executable program random.exe, you can display any two hexadecimal expression and the addition or subtraction operation result. In subtraction, if the minuend is less than the subtrahend, display " Divide Overflow"　of the message.