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

Example Input: uDaqoOpUtLDdTGTO, ncIgBjDPqoOpUtLDdTNtiEyarDO
Example Output: qoOpUtLDdT

Example Input: hGyDyQYdxCCuD, BQiFOyQYdxel
Example Output: yQYdx

Example Input: mMgALDSoFKdS, gELDSoFcGhuL
Example Output:
LDSoF