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: Male dogs use pheromones in urine to mark their territory. 
Sentence2: Pheromones are hormones that are thought to stimulate, through smell, sexual reactions in animals.

Ex Output:
pheromones


Ex Input:
Sentence1: Some mollusks are nearly microscopic. 
Sentence2: Some squids are nearly microscopic.

Ex Output:
Some


Ex Input:
Sentence1: By the simplest definition, a planet is a large object that orbits a star. 
Sentence2: gravity pulls objects towards large objects that orbit stars.

Ex Output:

large