用户从键盘输入2个任意长度的长整数，输入的时候是按4个为一段输入的,即一段一段输入的,求它们的乘积的大小，并将结果在屏幕上显示 2个长整数的输入没有大小的限制,要输入多大的数据,就可以输入多大的数据.-User input from the keyboard 2 long integers of arbitrary length, when the input is based on four inputs for the period that the input section by section, find the size of their product, and the results displayed on the screen　two long integers Enter no size restrictions, how to enter data, how much data can be entered.