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: Dams are very damaging to rivers. 
Sentence2: Creating a lake can be very damaging to rivers.

Ex Output:
damaging


Ex Input:
Sentence1: Fission is a type of reproduction, but a baby is the result of sexual reproduction. 
Sentence2: the fallopian tubes are used to make babies.

Ex Output:
baby


Ex Input:
Sentence1: Aggression is behavior that is intended to cause harm or pain. 
Sentence2: If they are around aggressive dogs, they learn to be aggressive.

Ex Output:

Aggression