instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
JqdTDnZqSuSVcMsx, TEtDDnZqSuZa
answer:
DnZqSu


question:
pJqqIW, Ivqqxw
answer:
qq


question:
TUPXGHFLrSRdRckiL, YCBXGHFLrSRqewXh
answer:

XGHFLrSR