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: Many corals secrete an exoskeleton that builds up to become a coral reef. 
Sentence2: Good examples are Bubble coral, Elegance coral, Frogspawn and other Euphyllia corals.

Ex Output:
coral


Ex Input:
Sentence1: Lymph is a fluid that leaks out of capillaries into spaces between cells. 
Sentence2: Humans are made up of trillions of cells.

Ex Output:
cells


Ex Input:
Sentence1: if a living thing becomes too cold then that living thing will die. 
Sentence2: If a thing becomes too cold then it will die and decompose only to be recylced again.

Ex Output:

becomes