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: Methane gas is a produced by rotting compost, trash, and human waste. 
Sentence2: Methane gas can be produced by Slime molds.

Ex Output:
Methane


Ex Input:
Sentence1: Scientists still know relatively little about Archaea. 
Sentence2: scientists still know relatively little about non-bacterial prokaryotes.

Ex Output:
Scientists


Ex Input:
Sentence1: Human birth is the rarest of all births. 
Sentence2: humans have a period of parental care of their offspring.

Ex Output:

Human