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: Many birds perform elaborate courtship dances. 
Sentence2: Many birds perform dances before they mate.

Ex Output:
Many


Ex Input:
Sentence1: Absorption of nutrients occurs mainly in the small intestine. 
Sentence2: The small intestine is the main place where food absorption occurs.

Ex Output:
intestine


Ex Input:
Sentence1: By far and away the biggest climate changes are ice ages. 
Sentence2: climate change can bury the planet in snow.

Ex Output:

changes