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: Mitosis is cell division. 
Sentence2: Chromosomes are the form of the genetic material of a cell during mitosis.

Output: Mitosis


Input: Consider Input: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: PALight Flashlights are the ultimate personal LED flashlights.

Output: flashlight


Input: Consider Input: Sentence1: Aging occurs as cells lose their ability to divide. 
Sentence2: Aging is when cells lose their ability to control their growth.


Output: Aging