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

Input: Consider Input: HEVqGddewrNqiZ, iyvlddewrNXr

Output: ddewrN

Input: Consider Input: mmDhYqPJC, qThYqxW

Output: hYq

Input: Consider Input: BlCNTtegvlQvvzBgSGLTstN, bSdQvvzBgSGLTHERg
Output: QvvzBgSGLT