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: Flatworms Flatworms or Platyhelminthes include flukes, tapeworms, and turbellarians. 
Sentence2: Tapeworms belong to the phylum Platyhelminthes.

Ex Output:
tapeworms


Ex Input:
Sentence1: igneous rocks are formed from magma cooling. 
Sentence2: magma solidifies into igneous rocks.

Ex Output:
magma


Ex Input:
Sentence1: Coyotes use their acute hearing and sense of smell to detect prey and avoid danger. 
Sentence2: Hearing is used for detecting prey and avoiding danger by animals.

Ex Output:

avoid