instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
HEVqGddewrNqiZ, iyvlddewrNXr
answer:
ddewrN


question:
ylyLVUjsmMrXMFAPDGIZsHq, cYymMrXMFAPjm
answer:
mMrXMFAP


question:
rbjaGECmvaxewuTWhzbnLI, OqKTzHcBpvaxewuTWhBgD
answer:

vaxewuTWh