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: mineral graphite is used for making pencil lead. 
Sentence2: Diamond and graphite are made of carbon.

Output: graphite


Input: Consider Input: Sentence1: Human mating behavior also involves some competition. 
Sentence2: Human mating may lead to aggressive behaviors or displays of aggresion.

Output: Human


Input: Consider Input: Sentence1: DNA contains genetic instructions for proteins, and RNA helps assemble the proteins. 
Sentence2: DNA acts as the store of genetic information.


Output: genetic