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: Minerals are chemical elements that are essential for body processes. 
Sentence2: minerals are needed by body processes.

Ex Output:
processes


Ex Input:
Sentence1: a fire requires oxygen to burn. 
Sentence2: If the oxygen is removed, the fire is smothered.

Ex Output:
oxygen


Ex Input:
Sentence1: a light bulb requires electrical energy to produce light. 
Sentence2: Additional track lighting brightens the overall space.

Ex Output:

light