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: An electric current is a flow of electric charge. 
Sentence2: a magnet moving in a coil of copper wire can cause a flow of electric charge.

Ex Output:
charge


Ex Input:
Sentence1: dew is formed when water vapor condenses over night. 
Sentence2: dew is formed when cooling  over night.

Ex Output:
dew


Ex Input:
Sentence1: erosion causes deposition. 
Sentence2: wind causes deposition.

Ex Output:

causes