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: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.

Output: Leeches


Input: Consider Input: Sentence1: faulting of rock in Earth 's crust causes earthquakes. 
Sentence2: fault movement forms earthquakes.

Output: earthquakes


Input: Consider Input: Sentence1: Smoking constricts arteries and increases clotting to block arteries. 
Sentence2: Smoking interferes with the transport of oxygen-rich blood in the body.


Output: Smoking