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: Spikes are forceful the tidal waves of electric current. 
Sentence2: spikes come from tidal energy.

Output: Spikes


Input: Consider Input: Sentence1: Heterotrophs are living things that cannot make their own food. 
Sentence2: food contains organic molecules.

Output: food


Input: Consider Input: Sentence1: Brain cells die quickly if their oxygen supply is cut off. 
Sentence2: Blood carries oxygen to the brain.


Output: oxygen