说明：  在一块M*N的棋盘上，给定棋子马的初始位置，找到它能遍历每个方格且不重复的路线，若没有，返回错误结果。其中M和N都是不小于2的整数。
(In a M* N chessboard, given the initial position of the pawn horse find can not duplicate routes traverse each square, and if not, return incorrect results. Wherein M and N are not less than an integer of 2.)