这个是一个VGA显示的程序，能够帮助初学者有效的理解VGA如何显示(This is a VGA display program that can help beginners effectively understand how VGA display)

按键输入四位数，长按功能键排序或者求最大公约数并显示在数码管上(Key input four digit, press function key sequence or for the common denominator and digital tube display)