instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
HiGmCdXrmFRJYWLvZbpU, IxhkrmFRJYWLvZLaqRVxPkL
answer:
rmFRJYWLvZ


question:
CUxfOt, dyxfNp
answer:
xf


question:
SkIujpbNuZhLgalyG, erRcvYRbNuZhLgalCwu
answer:

bNuZhLgal