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: Annelids have the amazing capacity to regrow segments that break off. 
Sentence2: Earthworms can regrow segments that break off.

Ex Output:
break


Ex Input:
Sentence1: if a neutral atom loses an electron then an atom with a negative charge will be formed. 
Sentence2: Ice crystals that are formed have a negative charge.

Ex Output:
charge


Ex Input:
Sentence1: Muscles can only contract. 
Sentence2: Contraction is a type of movement.

Ex Output:

contract