E. 2-Letter Stringstime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputGiven 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 \leq p \leq 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.InputThe first line of the input contains a single integer t (1 \le t \le 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 \le n \le 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.OutputFor 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 \leq p \leq 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++).ExampleInput
4
6
ab
cb
db
aa
cc
ef
7
aa
bb
cc
ac
ca
bb
aa
4
kk
kk
ab
ab
5
jf
jf
jk
jk
jk
Output
5
6
0
6
NoteFor 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.
4
6
ab
cb
db
aa
cc
ef
7
aa
bb
cc
ac
ca
bb
aa
4
kk
kk
ab
ab
5
jf
jf
jk
jk
jk

5 6 0 6 
['data structures', 'math', 'strings', '*1200']