Sometimes you may want to write a sentence into your nickname like "lubenwei niubi". But how to change it into a single word? Connect them one by one like "lubenweiniubi" looks stupid.

To generate a better nickname, Rikka designs a non-trivial algorithm to merge a string sequence s₁...s_n into a single string. The algorithm starts with s=s₁ and merges s₂...s_n into s one by one. The result of merging t into s is the shortest string r which satisfies s is a prefix of r and t is a subsequence of r.(If there are still multiple candidates, take the lexicographic order smallest one.)

String s is a prefix of r if and only if |s| ≤ |r| and for all index i ∈ [1, |s|], s_i = r_i.

String s is a subsequence of r if and only if there is an index sequence which satisfies .

For example, if we want to generate a nickname from "lubenwei niubi", we will merge "niubi" into "lubenwei", and the result is "lubenweiubi".

Now, given a sentence s₁...s_n with n words, Rikka wants you to calculate the resulting nickname generated by this algorithm.

The first line contains a single number t(1 ≤ t ≤ 3), the number of testcases.

For each testcase, the first line contains one single integer n(1 ≤ n ≤ 106).

Then n lines follow, each line contains a lowercase string .

For each testcase, output a single line with a single string, the result nickname.

2
2
lubenwei
niubi
3
aa
ab
abb

lubenweiubi
aabb