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: After a seed is planted it is watered. 
Sentence2: seeds need water.

Output: seed


Input: Consider Input: Sentence1: Osteoporosis is a disease characterized by a decrease in bone mineral density. 
Sentence2: a disease in which osteoclasts are more active than osteoblasts results in a decrease in bone mineral density.

Output: bone


Input: Consider Input: Sentence1: threatening behavior causes a fight-or-flight response in animals. 
Sentence2: True False Fight or flight are extreme responses to stress.


Output: fight-or-flight