摘要： Student Ilya often skips his classes at the university. His friends criticize him for this, but they don’t know that Ilya spends this time not watchin 阅读全文

摘要： Mr. Panda lives in Pandaland. There are many cities in Pandaland. Each city can be treated as a point on a 2D plane. Different cities are located in d 阅读全文