instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
NwmTIZSnlKGG, qAYIZSnfWRd
answer:
IZSn


question:
DQVkAbWTTPhoBx, TeWTTPhonxcIKL
answer:
WTTPho


question:
ctWEcHOltXDGLojXZ, XiSOnmsEcHOltXDqAqeVA
answer:

EcHOltXD