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:
JXnHYuZvAYK, zhUYuZvASGhd
answer:
YuZvA


question:
YhkMyJeFgsAXH, QNCkMyJeFgsuE
answer:

kMyJeFgs