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: Most water comes from precipitation. 
Sentence2: aquatic animals require precipitation to survive.

Output: precipitation


Input: Consider Input: Sentence1: cold fronts cause thunderstorms as they pass by. 
Sentence2: Thunderstorms create havoc.

Output: thunderstorms


Input: Consider Input: Sentence1: a plant requires sunlight for photosynthesis. 
Sentence2: Plants require nuclear reactions to grow.


Output: plant