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: jFVaEHbMrrkW, ekfVaEHbPnBnM
Example Output: VaEHb

Example Input: QiOILNAZznMOaDkVFpmTEQVYqLJW, PVIgznMOaDkVFpMQ
Example Output:
znMOaDkVFp