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: Flowers produce seeds for reproduction. 
Sentence2: flowers require dispersal for reproduction.

Output: Flowers


Input: Consider Input: Sentence1: an animal usually requires a warm body temperature for survival. 
Sentence2: Warm blooded animals have a constant body temperature.

Output: animal


Input: Consider Input: Sentence1: Climate is the average weather in an area over a long period of time. 
Sentence2: the average weather in Taiwan over a long period of time is subtropical.


Output: average