This problem is in Contest(s) below:
Contest 1017:2016永兴初一编程比赛
Contest 1018:2016银湖初一编程比赛
Contest 1402:【银实小】08 while循环
Contest 1328:【YH27Z】07 for循环结构练习一
Contest 1394:【YH28】07 for循环-练习一