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: a camera is used for recording images. 
Sentence2: a camera is used for recording binary.

Ex Output:
camera


Ex Input:
Sentence1: folding an object causes that object to change shape. 
Sentence2: Folding an object causes that object to transform.

Ex Output:
causes


Ex Input:
Sentence1: Experiments are often done in a lab. 
Sentence2: some researchers do experiments.

Ex Output:

Experiments