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:
iUtNuU, iKtNWk
answer:
tN


question:
SkeqWR, fBeqhi
answer:

eq