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

Example Input: vISTrmBMpQyanUTSXUCm, dJGyOHMpQyanUTpSb
Example Output: MpQyanUT

Example Input: TdvkBvVyJcSdYGGPfnyml, rIvIvVyJcSdYhtxG
Example Output: vVyJcSdY

Example Input: iexVzTmKOxaeALNsk, HWKSrtWKOxaeALgmpJmIP
Example Output:
KOxaeAL