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: Interstellar space contains a plasma. 
Sentence2: interstellar space contains electrons, atoms, and stars.

Ex Output:
Interstellar


Ex Input:
Sentence1: Insects spread disease and destroy crops. 
Sentence2: Crops are plants that are grown for food or other uses.

Ex Output:
crops


Ex Input:
Sentence1: high mountains with well-rounded peaks can be formed by collision of crustal plates. 
Sentence2: The Himalayas can be formed by collision of crustal plates.

Ex Output:

be