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

uZSRkFDHsGXNMaggxUn, lTrQKKpsGXNMaggEdSrEX
sGXNMagg

KfjqnJLciTXqkJK, yqfRcfqnJLcisSB
qnJLci

LiiFMMLGfNHVnnga, beXMMLGfNHVsjdfdN

MMLGfNHV