instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
sGrHRmELarByxp, cDCUnmELarBXbEfM
answer:
mELarB


question:
KvPFobZEGs, eKFobZEtnm
answer:
FobZE


question:
VpjfqznjYXUqHDKdo, ypvEIfznjYXUqNZKuI
answer:

znjYXUq