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:
DwLGzwYOWjtzIunE, TTViSbkwYOWjtzNqUOOz
answer:
wYOWjtz


question:
NNNooIwVsGpTcJd, AGoIwVsGXA
answer:

oIwVsG