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: Most people know that the Venus Flytrap is a carnivorous plant. 
Sentence2: The Venus Flytrap has specialized reproductive organs.

Ex Output:
Flytrap


Ex Input:
Sentence1: Mitosis is cell division. 
Sentence2: mitosis often causes growth.

Ex Output:
Mitosis


Ex Input:
Sentence1: Lakes are generally bigger and deeper than ponds. 
Sentence2: reservoirs are bigger and deeper than ponds.

Ex Output:

bigger