B'You are given n words of equal length m , consisting of lowercase Latin alphabet letters. The i -th word is denoted s_i . In one move you can choose any position in any single word and change the letter at that position to the previous or next letter in alphabetical order. For example: The difference between two words is the minimum number of moves required to make them equal. For example, the difference between "best" and "cost" is 1 + 10 + 0 + 0 = 11 . Find the minimum difference of s_i and s_j such that (i < j) . In other words, find the minimum difference over all possible pairs of the n words. The first line of the input contains a single integer t ( 1 <= t <= 100 ) -- the number of test cases. The description of test cases follows. The first line of each test case contains 2 integers n and m ( 2 <= q n <= q 50 , 1 <= q m <= q 8 ) -- the number of strings and their length respectively. Then follows n lines, the i -th of which containing a single string s_i of length m , consisting of lowercase Latin letters. For each test case, print a single integer -- the minimum difference over all possible pairs of the given strings. For the second test case, one can show that the best pair is ("abb","bef"), which has difference equal to 8 , which can be obtained in the following way: change the first character of the first string to 'b ' in one move, change the second character of the second string to 'b ' in 3 moves and change the third character of the second string to 'b ' in 4 moves, thus making in total 1 + 3 + 4 = 8 moves. For the third test case, there is only one possible pair and it can be shown that the minimum amount of moves necessary to make the strings equal is 35 . For the fourth test case, there is a pair of strings which is already equal, so the answer is 0 . '...