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=1＋2＋3.编程找出1000以内的所有完数。
(If a number is just equal to the sum of its factors, this number is called " End of a few." For example 6 = 1+2+3. Programmatically find all finished within a number of 1000.)