In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Q: YXsgPE, ENsgSO

A: sg
****
Q: yhhzISsXKEbA, KlPrazISsXKzmrVBG

A: zISsXK
****
Q: nDebeixwImKsirIRFKy, XceoImKsirIRFAjSU

A:
ImKsirIRF
****