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: weathering means breaking down rocks from larger whole into smaller pieces by weather. 
Sentence2: Trash collectors work in all types of weather, including rain and snow.

Ex Output:
weather


Ex Input:
Sentence1: the vanes rotating in an electric fan causes air to move. 
Sentence2: Vanes in a fan spinning causes air to move.

Ex Output:

air