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: when a body of water receives more water than it can hold , a flood occurs. 
Sentence2: Floods are deadly, floods are devastating.

Ex Output:
flood


Ex Input:
Sentence1: Sound vibrations travel at different speeds through different materials. 
Sentence2: the type of material through which sound passes changes the sound vibrations.

Ex Output:
Sound


Ex Input:
Sentence1: Polygenic inheritance Polygenic traits are controlled by an unknown number of genes. 
Sentence2: Skin color is inherited from a number of genes.

Ex Output:

genes