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: Eggs are usually laid in a nest. 
Sentence2: birds have nests.

Ex Output:
nest


Ex Input:
Sentence1: harming an animal species causes that animal 's population to decrease. 
Sentence2: Wild animal populations have decreased drastically, due to both hunting and loss of habitat.

Ex Output:
animal


Ex Input:
Sentence1: Temperature Temperature is an measurement of the amount of heat. 
Sentence2: A thermometer is used to measure the amount of heat.

Ex Output:

amount