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 is essential for all life on Earth. 
Sentence2: H2O is needed for all life on Eartth.

Ex Output:
Earth


Ex Input:
Sentence1: Many plants respond to the days growing shorter in the fall by going dormant. 
Sentence2: Many plants respond to the autumnal equinox by going dormant.

Ex Output:
Many


Ex Input:
Sentence1: a vehicle is used for transportation. 
Sentence2: Passenger vehicles are the primary mode of transportation.

Ex Output:

vehicle