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: Earthquakes cause massive damage. 
Sentence2: tectonic plates being pushed together causes massive damage.

Ex Output:
damage


Ex Input:
Sentence1: an animal requires air for survival. 
Sentence2: It is breathed in by animals and restored to the air by the photosynthesis mechanism of plants.

Ex Output:
air


Ex Input:
Sentence1: Weather refers to the circulation of the Earth's atmosphere. 
Sentence2: climate is the average circulation of the Earth's atmosphere over a long period of time.

Ex Output:

Earth's