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: Macroevolution is more than repeated rounds of microevolution. 
Sentence2: evolution over geologic time above the level of the species is more than repeated rounds of microevolution.

Output: microevolution


Input: Consider Input: Sentence1: Most water comes from precipitation. 
Sentence2: aquatic animals require precipitation to survive.

Output: precipitation


Input: Consider Input: Sentence1: When there is a release of pain, the nerve cells in the spinal cord are stimulated. 
Sentence2: stimuli can cause pain.


Output: pain