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: Any antigen that causes an allergy is called an allergen. 
Sentence2: Antigens are proteins foreign to the body.

Output: antigen


Input: Consider Input: Sentence1: Damage is intensified by moisture stress during drought. 
Sentence2: low amounts of rainfall intensify damage during drought.

Output: Damage


Input: Consider Input: Sentence1: friction causes the temperature of an object to increase. 
Sentence2: internal combustion engines get hot.


Output: temperature