A catenym is a pair of words separated by a period such that the last letter of the first word is the same as the first letter of the second. For example, the following are catenyms:
dog.gopher gopher.rat rat.tiger aloha.aloha arachnid.dog
A compound catenym is a sequence of three or more words separated by periods such that each adjacent pair of words forms a catenym. For example,
Given a dictionary of lower case words, you are to find a compound catenym that contains each of the words exactly once. The first line of standard input contains $t$, the number of test cases. Each test case begins with $3 \le n \le 1000$ – the number of words in the dictionary. $n$ distinct dictionary words follow; each word is a string of between 1 and 20 lowercase letters on a line by itself.
For each test case, output a line giving the lexicographically smallest compound catenym that contains each dictionary word exactly once. Output “***” if there is no solution.
|Sample Input 1||Sample Output 1|
2 6 aloha arachnid dog gopher rat tiger 3 oak maple elm