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: Temperature Scales Temperature is the energy of vibration. 
Sentence2: a thermometer is used to measure energy of vibration.

Ex Output:
energy


Ex Input:
Sentence1: Cells are the units of function in living things. 
Sentence2: living things cannot survive without oxygen.

Ex Output:
living


Ex Input:
Sentence1: Sweat wets the skin, and when it evaporates, it cools the body. 
Sentence2: humidity decreases sweat.

Ex Output:

Sweat