#P1669E. 2-Letter Strings
2-Letter Strings
Description
Given strings, each of length , consisting of lowercase Latin alphabet letters from 'a' to 'k', output the number of pairs of indices such that and the -th string and the -th string differ in exactly one position.
In other words, count the number of pairs () such that the -th string and the -th string have exactly one position () such that .
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 () — the number of test cases. The description of test cases follows.
The first line of each test case contains a single integer () — the number of strings.
Then follows lines, the -th of which containing a single string of length , consisting of lowercase Latin letters from 'a' to 'k'.
It is guaranteed that the sum of over all test cases does not exceed .
For each test case, print a single integer — the number of pairs () such that the -th string and the -th string have exactly one position () such that .
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++).
Input
The first line of the input contains a single integer () — the number of test cases. The description of test cases follows.
The first line of each test case contains a single integer () — the number of strings.
Then follows lines, the -th of which containing a single string of length , consisting of lowercase Latin letters from 'a' to 'k'.
It is guaranteed that the sum of over all test cases does not exceed .
Output
For each test case, print a single integer — the number of pairs () such that the -th string and the -th string have exactly one position () such that .
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.