More difficult C program works in ZJU. All the problems can be found in PTA system (pintia.cn).
因PTA有查重系统，为证明本人身份，避免不必要的麻烦，特此立据：
创建以本人中文姓名为内容的txt文档（编码为ANSI），其SHA1值为638B44794180A707A03A15856C3008B56BB8483E
Because the PTA has a check system, in order to prove that the certain student in PTA and me are the same person, and to avoid unnecessary troubles in the future, I think I need to give a proof here:
Create a txt file (coded as ANSI) with my Chinese name as its content, and its SHA1 value is 638B44794180A707A03A15856C3008B56BB8483E
The software here is open source under the MIT license.
This means that copying the code here without the LICENSE here is a violation of the agreement.
Therefore, it is recommended to check the code here instead of copying.