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.

Input: Consider Input: Sentence1: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Life without protein is impossible.

Output: proteins


Input: Consider Input: Sentence1: Lions live in social groups called prides. 
Sentence2: Chimpanzees live in social groups called communities.

Output: groups


Input: Consider Input: Sentence1: What semen is, is a carrier for the sperm contained in it. 
Sentence2: semen goes from male to female reproductive organs for fertilization.


Output: semen