write a go solution for Description:
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<=p<=2) such that s_i_pneqs_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.

Input Format:
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.

Output Format:
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<=p<=2) such that s_i_pneqs_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++).

Note:
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.. Output only the code with no comments, explanation, or additional text.