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.

Ex Input:
Sentence1: the moon revolving around the Earth causes the phases of the moon. 
Sentence2: Lets start our discussion of the Moon's phases with the New Moon phase.

Ex Output:
phases


Ex Input:
Sentence1: Centrioles come in pairs. 
Sentence2: Something that comes in pairs are organelles involved in cell division.

Ex Output:
come


Ex Input:
Sentence1: Reptiles are a class of tetrapod vertebrates that produce amniotic eggs. 
Sentence2: Lizards are tetrapod vertebrates that produce amniotic eggs.

Ex Output:

amniotic