instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
spGRUmIYuGl, qkqRUmItqU
answer:
RUmI


question:
oGaGjsaKsUpLQAg, iDGjsaKsUoYGuta
answer:
GjsaKsU


question:
SUDZYBLdw, wkAdDZYBLQg
answer:

DZYBL