This Christmas, you can get OI Wiki absolutely free. Also next Christmas. And the Christmas after that. Okay, it’s also available for free forever.

消息来源: https://t.me/thecruelworld/1804
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OI Wiki - OI Wiki
OI Wiki 是一个编程竞赛知识整合站点，提供有趣又实用的编程竞赛知识以及其他有帮助的内容，帮助广大编程竞赛爱好者更快更深入地学习编程竞赛