instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
DwLGzwYOWjtzIunE, TTViSbkwYOWjtzNqUOOz
answer:
wYOWjtz


question:
PIcbiJj, hedcbiZHF
answer:
cbi


question:
nWufFi, iCufBm
answer:

uf