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: Insect wings are attached to the dorsal side of their thorax. 
Sentence2: wings are attached to the dorsal side of the insect.

Ex Output:
dorsal


Ex Input:
Sentence1: Blood pH may become unbalanced if the rate of breathing is too fast or too slow. 
Sentence2: Slow and fast respirations or long periods without a breath are common in the dying child.

Ex Output:

breathing