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: Fertilization occurs naturally in the fallopian tubes. 
Sentence2: fertilization is used for reproduction.

Ex Output:
Fertilization


Ex Input:
Sentence1: Warm temperatures have helped plant growth and sizing. 
Sentence2: a greenhouse helps  plant growth.

Ex Output:
growth


Ex Input:
Sentence1: pushing on the pedals of a bike cause that bike to move. 
Sentence2: Bike shoes allow a rider to pull during the whole pedal stroke.

Ex Output:

pedals