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: First, the bottle is calibrated with a graduated cylinder. 
Sentence2: calibration is performed with a cylinder.

Ex Output:
calibrated


Ex Input:
Sentence1: if humans disturb animals in a location then those animals will move to a different location. 
Sentence2: The human being is self-aware.

Ex Output:
humans


Ex Input:
Sentence1: Friction is a Force that opposes motion. 
Sentence2: force that requires opposing motion causes the speed of an object to decrease.

Ex Output:

Force