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:
qMnjlfIsQRtUlPggCpHqu, gfVndMwYDIsQRtUlPgqBJKCX
answer:
IsQRtUlPg


question:
XhIzSxOe, uihwIzSxpvtB
answer:

IzSx