This problem is in Contest(s) below:
Contest 1930:2024语言提高结营测试
Contest 1862:单招测试题
Contest 1988:2025冬令营语言提高-最终测试
Contest 1825:2024语言基础班终极测试
Contest 1836:水平测试
Contest 1989:语言基础班终极测试
Contest 1933:2024语言基础A-结营测试