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: 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: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Life without protein is impossible.

Ex Output:
proteins


Ex Input:
Sentence1: Lymphocytes are the key cells involved in the immune response. 
Sentence2: Antibodies are synthesised by lymphocytes.

Ex Output:

Lymphocytes