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: when a river floods , that river deposits soil in flood plains. 
Sentence2: when a river floods, it deposits soil in generally marshy areas.

Ex Output:
deposits


Ex Input:
Sentence1: Most mammals have hair, or fur, covering their body. 
Sentence2: Most mammals have a body covering for keeping warm.

Ex Output:
body


Ex Input:
Sentence1: Lack of rain last winter has intensified Arizona's drought. 
Sentence2: lack of rain can change the color of an environment from green to brown.

Ex Output:

Lack