instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
sRpnJlgECTHh, JXfmNJlgECKyry
answer:
JlgEC


question:
ZKMRTxCxbsbX, iovHrMRTxCxbsjv
answer:
MRTxCxbs


question:
OavDWt, COvDJH
answer:

vD