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

VTwtMVKmrRvL, WLoVtWtMVKmrDCke
tMVKmr

UmYbssMbmsXkKQuzNasLOib, EMqlbmsXkKQuzNcyHrpZXOQW
bmsXkKQuzN

ZEIUaSbxCPZWKzDfcnZo, pgzcxCPZWKzDupkrPtZR

xCPZWKzD