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: Annelids have the amazing capacity to regrow segments that break off. 
Sentence2: Earthworms can regrow segments that break off.

Ex Output:
break


Ex Input:
Sentence1: Evaporation of sweat uses energy, and the energy comes from body heat. 
Sentence2: Evaporation of sweat uses energy, and the energy comes from exercise.

Ex Output:
Evaporation


Ex Input:
Sentence1: energy is used for heating a building by a heating system. 
Sentence2: Faculty offices are also in the building.

Ex Output:

building