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

Example Input: egYXVtCPvWxP, VMOolyVtCPvWjIx
Example Output: VtCPvW

Example Input: dxqZUOvRprXyFfjQfTWBhR, biSVjOvRprXyFfDtuFWQ
Example Output: OvRprXyFf

Example Input: hwyUjxhgwdp, FVmqjxhgDp
Example Output:
jxhg