Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Input: Consider Input: Sentence1: Cnidarians have a hydrostatic skeleton. 
Sentence2: Jellyfish have a hydrostatic skeleton.

Output: hydrostatic


Input: Consider Input: Sentence1: a mutation in the sex cells of a parent can cause a new trait to appear in the parent 's offspring. 
Sentence2: Traits are initiated by mutation and recombination.

Output: mutation


Input: Consider Input: Sentence1: Meteorologists are scientists who study the weather. 
Sentence2: predicting weather requires meteorologists.


Output: Meteorologists