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: Water erosion has similar consequences as wind erosion. 
Sentence2: exposure to water can cause erosion.

Ex Output:
Water


Ex Input:
Sentence1: Generally, pheromones are volatile substances. 
Sentence2: Male dogs use volatile substances in urine to mark their territory.

Ex Output:
substances


Ex Input:
Sentence1: weathering means breaking down rocks from larger whole into smaller pieces by weather. 
Sentence2: Weathering means eroding rocks down into smaller pieces of minerals.

Ex Output:

down