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: Many plants respond to the days growing shorter in the fall by going dormant. 
Sentence2: Many plants respond to the autumnal equinox by going dormant.

Ex Output:
Many


Ex Input:
Sentence1: If there is no movement friction is zero. 
Sentence2: Movement causes the temperature of an object to increase.

Ex Output:
movement


Ex Input:
Sentence1: when a metal rusts , that metal becomes orange on the surface. 
Sentence2: Rust stains are the result of oxidation.

Ex Output:

rusts