B'Given n strings, each of length 2 , consisting of lowercase Latin alphabet letters from 'a ' to 'k ', output the number of pairs of indices (i, j) such that i < j and the i -th string and the j -th string differ in exactly one position. In other words, count the number of pairs (i, j) ( i < j ) such that the i -th string and the j -th string have exactly one position p ( 1 <= q p <= q 2 ) such that {s_{i}}_{p} neq {s_{j}}_{p} . The answer may not fit into 32-bit integer type, so you should use 64-bit integers like long long in C++ to avoid integer overflow. 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 a single integer n ( 1 <= n <= 10^5 ) -- the number of strings. Then follows n lines, the i -th of which containing a single string s_i of length 2 , consisting of lowercase Latin letters from 'a ' to 'k '. It is guaranteed that the sum of n over all test cases does not exceed 10^5 . For each test case, print a single integer -- the number of pairs (i, j) ( i < j ) such that the i -th string and the j -th string have exactly one position p ( 1 <= q p <= q 2 ) such that {s_{i}}_{p} neq {s_{j}}_{p} . Please note, that the answer for some test cases won 't fit into 32-bit integer type, so you should use at least 64-bit integer type in your programming language (like long long for C++). For the first test case the pairs that differ in exactly one position are: ("ab", "cb"), ("ab", "db"), ("ab", "aa"), ("cb", "db") and ("cb", "cc"). For the second test case the pairs that differ in exactly one position are: ("aa", "ac"), ("aa", "ca"), ("cc", "ac"), ("cc", "ca"), ("ac", "aa") and ("ca", "aa"). For the third test case, the are no pairs satisfying the conditions. '...