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: Chromosomes are the form of the genetic material of a cell during cell division. 
Sentence2: Microtubules move the genetic material of a cell during cell division.

Output: cell


Input: Consider Input: Sentence1: ultraviolet light causes sunburn. 
Sentence2: Sunburn risk is higher at elevation.

Output: sunburn


Input: Consider Input: Sentence1: skin is used for protecting the body from harmful substances. 
Sentence2: Skin is comprised of two layers, the epidermis and dermis.


Output: skin