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: An example of a cartilaginous fish is a shark. 
Sentence2: jaws make sharks excellent predators.

Output: shark


Input: Consider Input: Sentence1: Speciation events are thus examples of macroevolution. 
Sentence2: Speciation events occur over geologic time above the level of the species.

Output: Speciation


Input: Consider Input: Sentence1: if an object is kicked then force is exerted on that object. 
Sentence2: When a force is exerted on an object, energy is transferred to the object.


Output: exerted