1.题中说"If there was more than one such round trip, he would have chosen the one which, when written down as a sequence of street numbers is lexicographically the smallest.",那么20 100 3应该怎样排序，是100 20 3，还是3 20 100？
2."Assume that Johnny lives at the junction ending the street No. 1 with smaller number",是否意味起始点在1号大街的编号较小的端点？
3." There exists a way from each street to another street in the town."是否表明每个测试数据都是连通图？