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: Ozone depletion results in higher levels of UV radiation reaching Earth. 
Sentence2: less ozone means more ultraviolet light.

Ex Output:
Ozone


Ex Input:
Sentence1: Ground tissue makes up most of the interior of a plant. 
Sentence2: ground tissue makes up most of the interior of a dandelion.

Ex Output:
Ground


Ex Input:
Sentence1: Antigens are found on cancer cells and the cells of transplanted organs. 
Sentence2: Organs such as the stomach and liver also begin to develop.

Ex Output:

organs