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: intense heat has a negative impact on an organism. 
Sentence2: intense heat has a negative impact on plants.

Ex Output:
heat


Ex Input:
Sentence1: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: if remains of prehistoric life are found in a place then that place used to be covered by water.

Ex Output:
be


Ex Input:
Sentence1: a speedometer is used for giving a driver feedback on the speed of their vehicle. 
Sentence2: Trucks and cars are vehicles.

Ex Output:

vehicle