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: a plant requires sunlight to grow. 
Sentence2: Grass needs air and sunlight.

Output: sunlight


Input: Consider Input: Sentence1: Many birds perform elaborate courtship dances. 
Sentence2: Many birds perform dances before they mate.

Output: Many


Input: Consider Input: Sentence1: Plants that are adapted to very dry environments are called xerophytes. 
Sentence2: cacti are xerophytes.


Output: xerophytes