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: Plants that shed their leaves seasonally each year are called deciduous plants. 
Sentence2: vines shed their leaves seasonally each year.

Ex Output:
each


Ex Input:
Sentence1: nectar is used for attracting pollinators by plants. 
Sentence2: butterflies pollinate plants.

Ex Output:
plants


Ex Input:
Sentence1: a breathing mask is used for keeping harmful particles from entering the respiratory system. 
Sentence2: Unlike larger particles, the smaller particles are able to enter the respiratory system.

Ex Output:

entering