instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
XZslQqrShfCXRXyHrFVq, BtOQgQqrShfCXRRCRbMvXPM
answer:
QqrShfCXR


question:
atDgsOWuP, UJMgsOrwj
answer:
gsO


question:
IrJmloTIqxu, oqbqJmloTIqLwrdnm
answer:

JmloTIq