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: the ovaries are used in reproduction. 
Sentence2: Unlike most female animals, which have two functioning ovaries, the chicken usually has only one.

Ex Output:
ovaries


Ex Input:
Sentence1: riding a bike does not cause pollution. 
Sentence2: riding a bike does not release particles.

Ex Output:
bike


Ex Input:
Sentence1: Landslides can be destructive. 
Sentence2: erosion can cause destruction.

Ex Output:

destructive