instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
dlzequypR, Puequqv
answer:
equ


question:
bUHPpvVtFQNSpUdg, zggEFoKBHPpvVtFQNHXsc
answer:
HPpvVtFQN


question:
PvvJRCHbSIwyxm, YBdkCRCHbSKhA
answer:

RCHbS