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: Mammalian teeth are important for digestion. 
Sentence2: bats' teeth are important for digestion.

Output: digestion


Input: Consider Input: Sentence1: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Lawns eat nitrogen.

Output: Nitrogen


Input: Consider Input: Sentence1: the volume of an object can be used to describe the size of that object. 
Sentence2: the volume of an object can be used to describe the dimensions of that object.


Output: describe