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

bUHPpvVtFQNSpUdg, zggEFoKBHPpvVtFQNHXsc
HPpvVtFQN

HXYkGv, GCYksu
Yk

IkzTQMUw, PNQTQMfGW

TQM