摘要：
Farmer John is an astounding accounting wizard and has realized he might run out of money to run the farm. He has already calculated and recorded the 阅读全文
摘要：
Natasha is planning an expedition to Mars for nn people. One of the important tasks is to provide food for each participant. The warehouse has mm dail 阅读全文
摘要：
A bracket sequence is a string containing only characters "(" and ")". A bracket sequence is a string containing only characters "(" and ")". A regula 阅读全文