instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OXdSmcKG, XbDdSmJl
answer:
dSm


question:
wcJmSloqlddFOfv, szhUIAqzSloqlddFDJz
answer:
SloqlddF


question:
yePbpoNXsDZKlGNhdChl, abslpoNXsDZKLJpSUTyM
answer:

poNXsDZK