FirstWord_How to handle dots

You are given a string where you have to find its first word. When solving a task pay attention to the following points: There can be dots and commas in a string. A string can start with a letter or, for example, a dot or space. A word can contain an apostrophe and it's a part of a word. The whole text can be represented with one word and that's it. Input: A string. Output: A string.

I don't know how to handle the dots,like "... and so on ...", could you helpl me? thanks!