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

GBTHKtWUzK, ovVNKtWUmVJF
KtWU

elloYaejTczBiiNOU, XoCPzloYaejTcXYtKODL
loYaejTc

gpIWPolkBfPxpTEehCIDvRy, zbYkBfPxpTEaTR

kBfPxpTE