看了一天的PSINS源码，脑袋都快炸了，但是仍然没看懂，我去，还要自己写函数，不会啊。晕死了。

Today,I was chatting with a girl.She is a gentle one.😊

It's difficult to prove definite integrals in exam math, so I have a long way to go, so I'll mull it over tomorrow.