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: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: Fossils of a water animal or plant are located in water-laid sediments.

Ex Output:
animal


Ex Input:
Sentence1: All cells share some of the same structures and basic functions. 
Sentence2: Inside the cell is a structure called the nucleus.

Ex Output:
cells


Ex Input:
Sentence1: Mammals breathe with the help of a diaphragm. 
Sentence2: humans breathe with the help of a diaphragm.

Ex Output:

breathe