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: Dinosaur bones, like many other artifacts, are fossilized. 
Sentence2: radioactive dating is used to determine the age of dinosaur bones.

Ex Output:
Dinosaur


Ex Input:
Sentence1: Fractures heal when osteoclasts form new bone. 
Sentence2: Fractures A fracture is a broken or cracked bone.

Ex Output:
Fractures


Ex Input:
Sentence1: Pugs are mammals and mammals shed. 
Sentence2: pugs have a layer of fat under the skin.

Ex Output:

Pugs