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

Q: qczzCr, zDzzUI

A: zz
****
Q: jLbHvZmecfxMcGLXGVsO, erFBGmecfxMcJtDyKGZ

A: mecfxMc
****
Q: AVOFNFynx, czUjFNFywxUE

A:
FNFy
****