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: Mating is generally preceded by courtship. 
Sentence2: Mating is generally similar across species.

Output: Mating


Input: Consider Input: Sentence1: An astronaut is a scientist who is a space explorer. 
Sentence2: Space explorers require preserved food for long flights.

Output: explorer


Input: Consider Input: Sentence1: Admiralty charts are maps designed for use as an aid to navigation at sea. 
Sentence2: Admiralty charts are maps that can help understand direction at sea.


Output: Admiralty