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: Sperm pass out of the body through the urethra. 
Sentence2: Sperm travel from the testicles through the vas deferens to the seminal vesicles and the prostate.

Ex Output:
Sperm


Ex Input:
Sentence1: Some birds are pollinators that co-evolved with plants. 
Sentence2: insects pollinate plants.

Ex Output:
plants


Ex Input:
Sentence1: Skin is an epithelial lining of the exposed parts of the body. 
Sentence2: Hookworm larvae enter the host through epithelial tissue.

Ex Output:

epithelial