instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
nYoRQU, gQoRZQ
answer:
oR


question:
SeXNqRAbKdLuWXgb, npsIWRAbKdLuUWSbvuS
answer:
RAbKdLu


question:
VYecHgMmp, NhcHglsR
answer:

cHg