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: An electric current is a flow of electric charge. 
Sentence2: a magnet moving in a coil of copper wire can cause a flow of electric charge.

Output: charge


Input: Consider Input: Sentence1: All chemical reactions require activation energy to get started. 
Sentence2: Catalysts lower the activation energy.

Output: activation


Input: Consider Input: Sentence1: a toaster converts electrical energy into heat energy for toasting. 
Sentence2: a toaster converts electrical energy into kinetic energy for toasting.


Output: converts