instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
kIBDjQLEZepVNHqnKqhine, hTZepVNHqnYTajyzv
answer:
ZepVNHqn


question:
CMrTXnTnTVaR, srnXnTnTDNULO
answer:
XnTnT


question:
QSuSAPGHUZHkCyJAqVTn, CDKLuImLAPGHUZHkXXXJsK
answer:

APGHUZHk