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

Example Input: ylyLVUjsmMrXMFAPDGIZsHq, cYymMrXMFAPjm
Example Output: mMrXMFAP

Example Input: inquDFuJxtBaaFGCaRzO, NYcnWDuDFuJxtBafxZWCUw
Example Output: uDFuJxtBa

Example Input: WfpRywfxYohkhX, mnMBbiYJpRywfxYoYGjz
Example Output:
pRywfxYo