//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

//以a_i表示其第i个元素所在的集合号

//输出格式为 a1 a2 a3 ...

//满足

//a_{i+1} <= max { a1,a2,...a_i } + 1

-/ / a given integer n, have all [2n] on the matching (matching) / / will be considered as an all pieces are two sets of a split / / a_i said in its i elements of a collection of lies / / output format for a1 a2 a3 ... / / meet / / a_ i (a)