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 uterus is used in reproduction. 
Sentence2: Reproduction uses the same organ as menstruation.

Ex Output:
reproduction


Ex Input:
Sentence1: Any antigen that causes an allergy is called an allergen. 
Sentence2: Antigens are proteins foreign to the body.

Ex Output:
antigen


Ex Input:
Sentence1: Slime molds are fungus-like protists commonly found on rotting logs and compost. 
Sentence2: The nonparasitic protists live on decaying trees and are fungus-like.

Ex Output:

fungus-like