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: Light source is an ultra-bright, unbreakable LED Bulb. 
Sentence2: LEDs convert electricity into light and heat energy.

Ex Output:
LED


Ex Input:
Sentence1: Asbestos is a dangerous carcinogen. 
Sentence2: Asbestos causes cancer.

Ex Output:
Asbestos


Ex Input:
Sentence1: a battery converts chemical energy into electrical energy. 
Sentence2: Cameras use batteries.

Ex Output:

battery