Way Too Long Words - The Idea

The trick is that abbreviation only makes sense when it shortens the word. A word of length $n$ abbreviates to at most 4 characters (like "a18b" where 18 is two digits). So if $n \leq 10$, the original word is short enough.

Keep it as-is. If $n > 10$, abbreviate it. The middle count is $n - 2$ because you keep the first and last characters. String indexing gives you easy access to any character. The first character is at index 0, the last at index $n-1$.

The middle count is just arithmetic: total length minus the two characters you keep.