| 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 | |