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

Example Input: bdCOjNchdKtvWzOI, FwejNchdKhEd
Example Output: jNchdK

Example Input: pqFpUjQGiofBOjfYkRW, pQMnCFlhFpUjQGiofbc
Example Output: FpUjQGiof

Example Input: PQNMlZnbZUBpGx, VrMlZnbZUBpDVfCJl
Example Output:
MlZnbZUBp