说明：  给定整数n，产生所有[2n]上的匹配（matching）//将其视为一个所有块大小均为2的集合分拆//输出格式为 a1 a2
( b1 b2- c1 c2- ...//满足a1< a2, b1< b2, ...//且 a1 < b1 < c1 < -given integer n, have all [2n] on the matching (matching)// will be considered as an all pieces are two sets of a split// output format for a1 a2-b2 b1- c1 c2-...// meet a1)