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

ykDpbd, YFDpmO
Dp

WFAPUCgVYbmZiFlacUzyv, xQFiekrgPUCgVYbmZUEtl
PUCgVYbmZ

CPtJuVNdGyWqwm, HtNeTtJuVNdGyWqhVl

tJuVNdGyWq