def dfs(wait,stack,out): if not wait and not stack: res.append(' '.join(map(str,out))) if wait:#进栈,先全部进栈 dfs(wait[1:],stack+[wait[0]],out) if stack:#出栈,一个个慢慢回调出栈 dfs(wait,stack[:-1],out+[stack[-1]]) n = int(input()) a = list(map(int,input().split()))#输入 res = []#存储结果的列表 dfs(a,[],[]) print('\n'.join(...