Description

Dr. lee cuts a string S into N pieces, s[1],s[2],…,s[n]. There might be several possibilities that the string S could be. For example, if Dr. lee gives you three substrings {“a”,”ab”,”ac”}, the string S could be “aabac”, “aacab”, “abaac”,…

Your task is to output the lexicographically smallest S.

Input

The first line of the input is a positive integer T. T is the number of the test cases followed. The first line of each case is a positive integer N(1<=N<=100) which represents the number of substrings. After that , N strings followed. Assume that the length of each substring is positive and less than 100.

Output

The output of each test is the lexicographically smallest S. No redundant spaces are needed.

Sample

Input

1
3
a ab ac

Output

aabac