instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
oHoJrr, YAoJSq
answer:
oJ


question:
MvALRGKkpALcKdhTtnm, neMkRGKkpALcKdcaxnXEPxW
answer:
RGKkpALcKd


question:
MtfvdSdh, npiIfvdSJDZh
answer:

fvdS