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: Endocrine glands include the pituitary, thyroid, parathyroid, adrenal, pineal and thymus glands. 
Sentence2: Some pituitary hormones can control the thyroid gland.

Ex Output:
thyroid


Ex Input:
Sentence1: For instance, glucose is a sugar. 
Sentence2: insulin helps cells take up sugar from the blood.

Ex Output:
sugar


Ex Input:
Sentence1: sandpaper is used to smooth wooden objects. 
Sentence2: Sandpaper can be used to smooth tables.

Ex Output:

sandpaper