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: Cells are the microscopic building blocks of organisms. 
Sentence2: proteins are the building blocks of organisms.

Ex Output:
organisms


Ex Input:
Sentence1: Dams are very damaging to rivers. 
Sentence2: Creating a lake can be very damaging to rivers.

Ex Output:
damaging


Ex Input:
Sentence1: a solar panel converts sunlight into electricity. 
Sentence2: Green plants and solar panels both capture energy from the sun.

Ex Output:

panel