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: triceps contracting causes a person 's elbow to straighten. 
Sentence2: muscles contracting cause a person's elbow to straighten.

Ex Output:
contracting


Ex Input:
Sentence1: Information on DNA is organized into genes. 
Sentence2: DNA codes for proteins.

Ex Output:
DNA


Ex Input:
Sentence1: Some viruses live in a dormant state inside the body. 
Sentence2: When ferns are dormant it is as if they are hibernating.

Ex Output:

dormant