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.

Input: Consider Input: Sentence1: Germination depends on the seed coat. 
Sentence2: the force of water causes germination with the emergence of a root.

Output: Germination


Input: Consider Input: Sentence1: Any antigen that causes an allergy is called an allergen. 
Sentence2: molds are antigens.

Output: antigen


Input: Consider Input: Sentence1: Cottages are heated by gas space heat or gas furnaces. 
Sentence2: gas expands after going through a furnace into a cottage.


Output: Cottages