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: Most copepods feed on phytoplankton. 
Sentence2: most copepods feed on bacteria and algae that use sunlight to make food.

Output: copepods


Input: Consider Input: Sentence1: hunting requires seeing prey. 
Sentence2: hunting requires seeing an animal.

Output: hunting


Input: Consider Input: Sentence1: All light is energy, which is eventually absorbed and turned into heat. 
Sentence2: Light energy causes objects to warm up.


Output: energy