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: Bryophytes occupy niches in moist habitats. 
Sentence2: Animals and plants that live in the same place and share resources form a community biome niche .

Output: niches


Input: Consider Input: Sentence1: microbial fuel cells convert chemical energy into electrical energy. 
Sentence2: microbial fuel cells convert chemical energy into kinetic energy.

Output: cells


Input: Consider Input: Sentence1: Populations of viruses do not grow through cell division because they are not cells. 
Sentence2: Cancer is not caused by viruses.


Output: not