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 flashlight converts chemical energy into light energy. 
Sentence2: Only as long as there are batteries in the flashlight, the flashlight will function.

Ex Output:
flashlight


Ex Input:
Sentence1: Boiling water can cause burns. 
Sentence2: heating water can cause burns.

Ex Output:
water


Ex Input:
Sentence1: The pancreas is an organ that is part of our digestive system. 
Sentence2: The pancreas is important for breaking food into nutrients for our bodies.

Ex Output:

pancreas