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

zqRbqwgmqGIAGTeeoGFOSr, RFnLqwgmqGIAGLcEvAWxY
qwgmqGIAG

XbjDHRCWxdPbhibUKn, SrpuPDHRCWxdPbKPWEXNWbZ
DHRCWxdPb

kyQNzVNnhLiESm, uQOqowlQNzVNnhiWb

QNzVNnh