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: friction is used for stopping a vehicle by brakes. 
Sentence2: friction is used for stopping a car by brakes.

Ex Output:
brakes


Ex Input:
Sentence1: Hermit crabs use the shells of dead snails for homes. 
Sentence2: Hermits crabs use dead snails shells as their place to live.

Ex Output:
Hermit


Ex Input:
Sentence1: plant requires seed dispersal for reproduction. 
Sentence2: plants require fruits for reproduction.

Ex Output:

plant