摘要： DescriptionBefore the invention of book-printing, it was very hard to make a copy of a book. All the contents had to be re-written by hand by so calle... 阅读全文

摘要： DescriptionOnce Bob took a paper stripe ofnsquares (the height of the stripe is 1 square). In each square he wrote an integer number, possibly negativ... 阅读全文

摘要： DescriptionVanya walks late at night along a straight street of lengthl, lit bynlanterns. Consider the coordinate system with the beginning of the str... 阅读全文