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

Q: jinzsW, SMnzaW

A: nz
****
Q: wbdHVigIkjNkuAmbr, iSgIkjNkQYyn

A: gIkjNk
****
Q: HfgFLc, gLgFsK

A:
gF
****