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

Q: RtOkkgLvhgfGlX, vCOkgLvhzOa

A: kgLvh
****
Q: zBNTHKtofMdHfBgJhOfojzM, VIkVdFapofMdHfBgjPCUo

A: ofMdHfBg
****
Q: RYIfkRGtQm, ogFIfkRGZZla

A:
IfkRG
****