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.

Ex Input:
Sentence1: Minerals are chemical elements that are essential for body processes. 
Sentence2: minerals are needed by body processes.

Ex Output:
processes


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

Ex Output:
Human


Ex Input:
Sentence1: Metals conduct heat well. 
Sentence2: metals are good conductors.

Ex Output:

Metals