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

Q: vhZuXCsIkQR, YflCuXCsIkLu

A: uXCsIk
****
Q: bUHPpvVtFQNSpUdg, zggEFoKBHPpvVtFQNHXsc

A: HPpvVtFQN
****
Q: fSyBUqtxNHdM, catDUqtxiYGS

A:
Uqtx
****