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

TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK
YjBCeUpy

fAsWQxuyBevvLogrSrgg, tmdBEUxuyBevvLogXjiMCbh
xuyBevvLog

ylyLVUjsmMrXMFAPDGIZsHq, cYymMrXMFAPjm

mMrXMFAP