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: Many birds perform elaborate courtship dances. 
Sentence2: Many birds perform dances before they mate.

Output: Many


Input: Consider Input: Sentence1: Humans have collected and grown mushrooms for food for thousands of years. 
Sentence2: Yeast and mushrooms are types of fungus.

Output: mushrooms


Input: Consider Input: Sentence1: Eggs are usually laid in a nest. 
Sentence2: Quetzals nest in rotting trees.


Output: nest