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

cfvqbAUpWEmhCSFaUvGrYVNGeUiRP, hAxWMEmhCSFaUvGLBLmdTxhy
EmhCSFaUvG

OBzHWjmkcgVGPyv, gCHWjmkcgVMq
HWjmkcgV

ZFzEtVCqHtLmKEGH, rSPBIoLEtVCqHtLmKjpPnAP

EtVCqHtLmK