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

Example Input: ezVsFayUPcrte, lfsFayUMPTqx
Example Output: sFayU

Example Input: hcmMoVBhK, mdmMoVBjuT
Example Output: mMoVB

Example Input: OfSbfUSMAuiochFXzN, cSaSybfUSMAuiosWyazv
Example Output:
bfUSMAuio