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

Example Input: UysTOtIRtRorNAFKKYD, icDOtIRtRoropYVaKzJ
Example Output: OtIRtRor

Example Input: OVVkkdeHoFlyNROyCP, zFVUJbvkkdeHoFlysF
Example Output: kkdeHoFly

Example Input: BeoubQyiiZZVvP, kNBCbQyiiRwrQ
Example Output:
bQyii