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

Example Input: yjoJzBGdwfOhsceoOpoap, uSLMdBGdwfOhsIQHBijd
Example Output: BGdwfOhs

Example Input: HaIPcFXLhYDp, AdIPcFXtJdRE
Example Output: IPcFX

Example Input: BnLMwTFRvbgrmnvtyyT, vrhvsomxhiTFRvbgrmnvhjakbuRlqU
Example Output:
TFRvbgrmnv