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.

Ex Input:
Sentence1: an animal requires nutrients to grow and heal. 
Sentence2: Microbes can help an animal to grow and heal.

Ex Output:
grow


Ex Input:
Sentence1: friction causes the temperature of an object to increase. 
Sentence2: internal combustion engines get hot.

Ex Output:
temperature


Ex Input:
Sentence1: Cells are programmed to divide only a set number of times. 
Sentence2: Cells reproduce asexually, by dividing.

Ex Output:

divide