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: Soil Erosion Soil erosion is a natural process.
Sentence2: wind and rain is a natural process.

Ex Output:
natural

Ex Input:
Sentence1: Moist air is forced up the mountains bringing both cloud and precipitation to the windward side.
Sentence2: moist air falls on the windward side of a mountain.

Ex Output:
Moist