CF342A.Xenia and Divisors

Xenia the mathematician has a sequence consisting of n (n is divisible by 3) positive integers, each of them is at most 7. She wants to split the sequence into groups of three so that for each group of three a, b, c the following conditions held:

• a < b < c;
• a divides b, b divides c.

Naturally, Xenia wants each element of the sequence to belong to exactly one group of three. Thus, if the required partition exists, then it has groups of three.

Help Xenia, find the required partition or else say that it doesn't exist.

数学家 Xenia 有一个由 $ n $（$ n $ 能被 3 整除）个正整数组成的序列，每个数都不超过 7。她希望将该序列划分为若干个三元组，使得对每个三元组 $ a,,b,,c $ 均满足以下条件：

• $ a < b < c $；
• $ a $ 整除 $ b $，且 $ b $ 整除 $ c $。

显然，Xenia 希望序列中的每个元素恰好属于一个三元组。因此，若所求划分存在，则它恰好包含 个三元组。

请帮助 Xenia 找到满足要求的划分；若不存在这样的划分，请说明其不存在。

The first line contains integer n (3 ≤ n ≤ 99999) — the number of elements in the sequence. The next line contains n positive integers, each of them is at most 7.

It is guaranteed that n is divisible by 3.

第一行包含一个整数 $n$（$3 \leq n \leq 99999$）—— 表示序列中元素的个数。
下一行包含 $n$ 个正整数，每个数都不超过 $7$。

保证 $n$ 能被 $3$ 整除。

If the required partition exists, print groups of three. Print each group as values of the elements it contains. You should print values in increasing order. Separate the groups and integers in groups by whitespaces. If there are multiple solutions, you can print any of them.

If there is no solution, print -1.

如果存在满足要求的划分，输出 组，每组包含三个元素。对每组，按升序输出其所含元素的值。组与组之间、组内各整数之间均以空格分隔。若存在多种解，输出任意一种即可。

若不存在解，则输出 -1。