instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
YlhtTQgHiffTbIbBrcHMqFKCdWz, HyregFgMffTbIbBrcHYUnnQvGlx
answer:
ffTbIbBrcH


question:
QKlzsmHyBcC, snPtzsmHdMIv
answer:
zsmH


question:
fFJnuR, EEJnMQ
answer:

Jn