| You've been given a list of words to study and memorize. Being a diligent |
| student of language and the arts, you've decided to not study them at all and |
| instead make up pointless games based on them. One game you've come up with is |
| to see how you can concatenate the words to generate the lexicographically |
| lowest possible string. |
| |
|
|
| ### Input |
|
|
| As input for playing this game you will receive a text file containing an |
| integer **N**, the number of word sets you need to play your game against. |
| This will be followed by **N** word sets, each starting with an integer **M**, |
| the number of words in the set, followed by **M** words. All tokens in the |
| input will be separated by some whitespace and, aside from **N** and **M**, |
| will consist entirely of lowercase letters. |
| |
|
|
| ### Output |
|
|
| Your submission should contain the lexicographically shortest strings for each |
| corresponding word set, one per line and in order. |
| |
|
|
| ### Constraints |
|
|
| 1 ≤ **N** ≤ 100 |
| 1 ≤ **M** ≤ 9 |
| 1 ≤ all word lengths ≤ 10 |
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|
