instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
VByrCcgcxCfPGDFqIWGloQZTMQf, OqfPGDFqIWGlalTCCkKkMf
answer:
fPGDFqIWGl


question:
wkVVZREWhcSCpvCTB, ZQWhcSCpvCDVUY
answer:
WhcSCpvC


question:
KpCIXT, KSCIlg
answer:

CI