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: Moisture is required for the microorganisms to grow. 
Sentence2: Moisture can cause infections to grow.

Ex Output:
Moisture


Ex Input:
Sentence1: Fractures heal when osteoclasts form new bone. 
Sentence2: Fractures A fracture is a broken or cracked bone.

Ex Output:
Fractures


Ex Input:
Sentence1: An insect visitor is required for pollination and they have a mixed mating system. 
Sentence2: plant reproduction requires An insect.

Ex Output:

An