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 pulley is used for lifting objects. 
Sentence2: Resistance exercises are weight-lifting exercises.

Output: lifting


Input: Consider Input: Sentence1: Babies that are very large or very small at birth are less likely to survive. 
Sentence2: Babies that are very large or very small at birth are less likely to live.

Output: Babies


Input: Consider Input: Sentence1: Ancestors of hagfish are thought to have been the earliest vertebrates. 
Sentence2: some vertebrates have no hard tissues.


Output: vertebrates