说明：  一个数如果恰好等于它的因子之和，这个数就称为完数。例如，6的因子为1、2、3，而6=1+2+3，因此6是完数。编程求1000以内所有完数。
(If a number is exactly equal to the sum of its factors, this number is called the complete number. For example, the 6 factor is 1, 2, 3, and 6=1+2+3, so the number 6 is finished. Programming for less than 1000 of all the number of.)