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: Some viruses live in a dormant state inside the body. 
Sentence2: a virus can live in the brain.

Ex Output:
viruses


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: Jellyfish and insects are invertebrates. 
Sentence2: jellyfish have a nervous system.

Ex Output:

Jellyfish