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: Algae have varied life cycles. 
Sentence2: And fish eat algae.

Output: Algae


Input: Consider Input: Sentence1: boiling means change from a liquid into a gas by adding heat energy. 
Sentence2: boiling changes a liquid into steam.

Output: liquid


Input: Consider Input: Sentence1: medicine is used for curing people when they are sick. 
Sentence2: Drugs are small medicine.


Output: medicine