Some pairs of letters appear frequently next to each other in words.
For example, 'a' and 't' appear twice consecutively in the word "attach", and also twice in the word "tattoo".
We don't care about the order in which they appear ("ta" or "at") or if the same letter is counted twice in the same word (thus we count two occurrences in "tat", for the same letters).
You will be given a String words, where each element is a single word. Find the pair of letters that appear next to each other most frequently, and return the number of times that pair appears in the entire list.