instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
HEVqGddewrNqiZ, iyvlddewrNXr
answer:
ddewrN


question:
OezHeoe, ouUzHemU
answer:
zHe


question:
QgkpBHsrfRYJCa, AdjbKLpBHsrfbpBC
answer:

pBHsrf