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: Sex hormones are chemical messengers that control sexual development and reproduction. 
Sentence2: Androgens are male sex hormones.

Output: Sex


Input: Consider Input: Sentence1: creating paper requires cutting down trees. 
Sentence2: Trees begin as epiphytes on host trees.

Output: trees


Input: Consider Input: Sentence1: Electric power is ready to use at the flip of a switch. 
Sentence2: current flow gives electric power.


Output: Electric