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

DwkTGsIXLfmjMV, VqRlMxtsSBkTGsIXLfmjbvI
kTGsIXLfmj

OyXwTWbLByC, yODnTWbLWYzc
TWbL

gXQIvmA, mQdQIvfji

QIv