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

Q: qMnjlfIsQRtUlPggCpHqu, gfVndMwYDIsQRtUlPgqBJKCX

A: IsQRtUlPg
****
Q: MSzHyOuaJILkeY, eUibEHoHyOuaJIhfvXy

A: HyOuaJI
****
Q: NsVzDE, efVznD

A:
Vz
****