有一个城市的道路由规则的方砖组成。有一位数学家来参观，他可沿方砖的边沿行走，有四种方法：n(0,1)，s(0,-1)，e(1,0)，w(-1,0)，但他是一个很怪的数学家，他会走一段时间休息一会儿，然后继续走。他有几个很特别的特性-A city road by the rules of cubes formed. A mathematician to visit, he can walk along the edge of squares, there are four methods: n (0,1), s (0,-1), e (1,0), w (-1,0) But he is a strange mathematician, he would take some time to rest for a while, and then continue walking. He has several very special features