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.

Ex Input:
Sentence1: Rainy clouds cause rain, and excess water vapor from clouds is the basis of rainbows. 
Sentence2: Condensation can lead to rain.

Ex Output:
rain


Ex Input:
Sentence1: Most genes contain the instructions for a single protein. 
Sentence2: Most genes contain the instructions for protein destinations.

Ex Output:
Most


Ex Input:
Sentence1: the vanes rotating in an electric fan causes air to move. 
Sentence2: Output of the fan is varied by means of a series of adjustable vanes upstream of the impeller.

Ex Output:

vanes