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: Most bryophytes are small. 
Sentence2: Most in the same group as mosses are small.

Output: small


Input: Consider Input: Sentence1: Silica sand is primarily mined from sandstone deposits. 
Sentence2: erosion forms silica sand.

Output: Silica


Input: Consider Input: Sentence1: Cells secrete acids and bases to maintain the proper pH for enzymes to work. 
Sentence2: An enzyme is a biological catalyst .


Output: enzymes