This problem is in Contest(s) below:
Contest 1511:函数
Contest 1335:分支结构练习题
Contest 1452:四班练习题3
Contest 1054:初二小盆友
Contest 1177:初一小朋友训练
Contest 1180:2018小六第一场
Contest 1294:2018新小六加题(1)
Contest 1354:穷举
Contest 1445:2019小六循环练习3
Contest 1508:初一小朋友循环回顾
Contest 1280:2018小六练习
Contest 1490:2019寒假初一(1)班入门练习(3)
Contest 1491:2019寒假初一(3)班入门练习(3)
Contest 1307:2018寒假初一新生练习(3)
Contest 1482:寒假入门2班
Contest 1162:初一小朋友寒假作业
Contest 1387:求和
Contest 1365:训练111