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: Most bryophytes are small. 
Sentence2: Most in the same group as mosses are small.

Ex Output:
small


Ex Input:
Sentence1: Osteoporosis is a disease in which osteoclasts are more active than osteoblasts. 
Sentence2: a thinning and weakening of bone is a disease in which osteoclasts are more active than osteoblasts.

Ex Output:
active


Ex Input:
Sentence1: Ants communicate with chemicals called pheromones. 
Sentence2: Ants communicate via chemicals excreted by their bodies.

Ex Output:

Ants