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

Output: living


Input: Consider Input: Sentence1: Translation reads the genetic code in mRNA and makes a protein. 
Sentence2: Nucleotide sequences are read in mRNA and a protein is made.

Output: mRNA


Input: Consider Input: Sentence1: Electrical energy can be converted into kinetic energy and heat energy by an electric motor. 
Sentence2: Microbial fuel cells convert chemical energy into something that can be converted into kinetic energy and heat energy by a motor.


Output: converted