这可是一个难过的暑假哇，别白过

                                    C. Lorenzo Von Matterhorn Barney lives in NYC. NYC has infinite number of intersections numbered with positive integers starting from 1. There exists abidirectiona...

                                             D. Puzzles Barney lives in country USC (United States of Charzeh). USC has n cities numbered from 1 through n and n - 1 roads between them. Cities and roa...