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

Q: XwBMFIV, SNLBMFZQ

A: BMF
****
Q: rPPfxUdowLLdvwRtY, PuHovApkfxUdowLLBOhq

A: fxUdowLL
****
Q: JuXDGUpT, veXDGUEMaf

A:
XDGU
****