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: keeping food cold is used for keeping food fresh. 
Sentence2: Keeping food cold is used to keep food simple and natural as possible.

Output: cold


Input: Consider Input: Sentence1: the Earth being tilted on its rotating axis causes seasons. 
Sentence2: the planet's orbit and tilt causes seasons.

Output: seasons


Input: Consider Input: Sentence1: Genetics is the study and application of principles of inheritance to plants and animals . 
Sentence2: Pedigrees are useful tools for studying Genetics.


Output: Genetics