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: healing requires rest. 
Sentence2: healing requires time.

Output: healing


Input: Consider Input: Sentence1: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: Common fossils include plant fossils like ferns.

Output: plant


Input: Consider Input: Sentence1: measuring the hardness of minerals requires scratching those materials. 
Sentence2: Getting a measurement on the Moh's scale requires scratching.


Output: measuring