Keine has the ability to manipulate history.
The history of Gensokyo is a string ss of length 11 initially. To fix the chaos caused by Yukari, she needs to do the following operations nn times, for the ii-th time:
Note that if t2i−1t2i−1 occurs more than once in ss, exactly one of them will be replaced.
For example, let s=s="marisa", t2i−1=t2i−1="a", and t2i=t2i="z". After the operation, ss becomes "mzrisa" or "marisz".
After nn operations, Keine got the final string and an operation sequence tt of length 2n2n. Just as Keine thinks she has finished, Yukari appears again and shuffles the order of tt. 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.
Each test contains multiple test cases. The first line contains a single integer TT (1≤T≤1031≤T≤103) — the number of test cases. The desc
The first line of each test case contains a single integer nn (1≤n<1051≤n<105) — the number of operations.
The next 2n2n lines contains one non-empty string titi — the ii-th string of the shuffled sequence tt.
The next line contains one non-empty string ss — the final string.
It is guaranteed that the total length of given strings (including titi and ss) over all test cases does not exceed 2⋅1052⋅105. 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.
For each test case, print the initial string in one line.
2
2
a
ab
b
cd
acd
3
z
a
a
aa
yakumo
ran
yakumoran
a
z