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

Example Input: VByrCcgcxCfPGDFqIWGloQZTMQf, OqfPGDFqIWGlalTCCkKkMf
Example Output: fPGDFqIWGl

Example Input: gWMyioGBRpwcXfr, AOQGBRpwcSccqBE
Example Output: GBRpwc

Example Input: egkVOpUawiZKgg, VdxeNtZpUawiZKljZBj
Example Output:
pUawiZK