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

RwqzMTeLMdPx, qaWtYhqzMTeLMdHbWDT
qzMTeLMd

WTnsmP, INnsIM
ns

UpKFxSAbkWCSfGR, MbdmxSAbkWCSxFmVO

xSAbkWCS