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: Most major Atlantic hurricanes start as small disturbances moving westward off Africa. 
Sentence2: When something that starts as a small disturbance moving westward off Africa then moves over land, it will decrease in strength.

Ex Output:
Africa


Ex Input:
Sentence1: An accounting period is simply a period of time. 
Sentence2: seconds are used to measure a period.

Ex Output:
period


Ex Input:
Sentence1: Tides create current. 
Sentence2: The gravitational pull of the Moon on Earth's ocean contributes to ocean currents.

Ex Output:

current