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

Example Input: UTdardKNThdYrGKMqZPeg, mvrThdYrGKMlcCxBtak
Example Output: ThdYrGKM

Example Input: jJjsASFfCqVV, AkjsASFfBFwPy
Example Output: jsASFf

Example Input: MqrnTfsdVAbGdZKGyiXSLyI, twAeFYwTfsdVAbGdZuxil
Example Output:
TfsdVAbGdZ