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

vhZuXCsIkQR, YflCuXCsIkLu
uXCsIk

zzEhnt, sYEhtc
Eh

DcpTtduxxWfVs, VbUmqduxxWWsHK

duxxW