instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
trHTzJpm, aCHTzVVA
answer:
HTz


question:
QgkpBHsrfRYJCa, AdjbKLpBHsrfbpBC
answer:
pBHsrf


question:
wcbpRxeU, csbpROW
answer:

bpR