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: Allergens can trigger asthma attacks.

Output: allergen


Input: Consider Input: Sentence1: a magnet moving in a coil of copper wire can cause an electric current. 
Sentence2: An electric current forms when a magnet is run through an induction coil.

Output: current


Input: Consider Input: Sentence1: magnetism can cause objects to repel each other. 
Sentence2: magnetism is the force that causes objects to push or attract each other.


Output: cause