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: Bivalves feed on plankton and nonliving organic matter. 
Sentence2: Clams feed on plankton and nonliving organic matter.

Ex Output:
feed


Ex Input:
Sentence1: Ground tissue makes up most of the interior of a plant. 
Sentence2: ground tissue makes up most of the interior of a dandelion.

Ex Output:
Ground


Ex Input:
Sentence1: Arthropods are the largest phylum of invertebrates. 
Sentence2: insects are arthropods.

Ex Output:

Arthropods