A common problem in data structures is to determine the traversal of a binary tree. There are three classic ways to do it:

Pre-order: You must visit in
sequence the root, left subtree and the right subtree.

In-order: You must visit
in sequence the left subtree, the root and the right subtree.

Post-order: You must visit in
sequence the left subtree, the right subtree and the root.

See the picture below:

The pre, in and post-order traversal are, respectively,
ABCDEF, CBAEDF and CBEFDA. In this problem, you must compute the post-order
traversal of a binary tree given its in-order and pre-order traversals.

The input set consists of a positive number **C ≤ 2000**, that
gives the number of test cases and C
lines, one for each test case. Each test case starts with a number** 1
≤** N**
≤ 52**, the number of nodes in this binary tree. After, there will be
two strings **S _{1} **and

For each input set, you should output a line containing the post-order
transversal for the current tree.

3

3 xYz Yxz

3 abc cba

6 ABCDEF CBAEDF

Yzx

cba

CBEFDA

Problem setter: Sebastião Alves