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.

Input: Consider Input: Sentence1: With a spatula, fold in flour mixture. 
Sentence2: a sifter is used for separating flour.

Output: flour


Input: Consider Input: Sentence1: Complex chemistry is needed to carry out all the functions of life. 
Sentence2: Chemistry is primarily concerned with matter, energy, and their interactions.

Output: chemistry


Input: Consider Input: Sentence1: Loss of ozone has created an ozone hole over Antarctica. 
Sentence2: Ozone Ozone is one form of oxygen.


Output: ozone