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: condensing causes a liquid to form. 
Sentence2: Air carries moisture that causes a liquid to form.

Output: causes


Input: Consider Input: Sentence1: Small stalactites predominate on the cave roof. 
Sentence2: cave roofs are formed by deposition.


Output: cave