Keine has the ability to manipulate history.
The history of Gensokyo is a string s of length 1 initially . To fix the chaos caused by Yukari, she needs to do the following operations n times, for the i-th time:
Note that if t_2i-1 occurs more than once in s, exactly one of them will be replaced.
For example, let s=" marisa ", t_2i-1=" a ", and t_2i=" z ". After the operation, s becomes " mzrisa " or " marisz ".
After n operations, Keine got the final string and an operation sequence t of length 2n. Just as Keine thinks she has finished, Yukari appears again and shuffles the order of t. Worse still, Keine forgets the initial history.
Help Keine find the initial history of Gensokyo!
Recall that a substring is a sequence of consecutive characters of the string. For example, for string " abc " its substrings are: " ab ", " c ", " bc " and some others. But the following strings are not its substring: " ac ", " cba ", " acb ".
Hacks
You cannot make hacks in this problem.
Input
Each test contains multiple test cases. The first line contains a single integer T (1 ≤ T ≤ 10^3) — the number of test cases. The description of the test cases follows.The first line of each test case contains a single integer n (1 ≤ n 10 ^ 5) — the number of operations.The next 2n lines contains one non-empty string t_i — the i-th string of the shuffled sequence t.The next line contains one non-empty string s — the final string.It is guaranteed that the total length of given strings (including t_i and s) over all test cases does not exceed 2 · 10 ^ 5. All given strings consist of lowercase English letters only.It is guaranteed that the initial string exists. It can be shown that the initial string is unique.
Output
For each test case, print the initial string in one line.
Examples
Note
Test case 1:Initially s is "a". In the first operation, Keine chooses "a", and replaces it with "ab". s becomes "ab". In the second operation, Keine chooses "b", and replaces it with "cd". s becomes "acd".So the final string is "acd", and t=["a", "ab", "b", "cd"] before being shuffled.Test case 2:Initially s is "z". In the first operation, Keine chooses "z", and replaces it with "aa". s becomes "aa". In the second operation, Keine chooses "a", and replaces it with "ran". s becomes "aran". In the third operation, Keine chooses "a", and replaces it with "yakumo". s becomes "yakumoran".So the final string is "yakumoran", and t=["z", "aa", "a", "ran", "a", "yakumo"] before being shuffled.