instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
tWJoKSOAuVhmsomA, emdmnBFJoKSOAuVzSgW
answer:
JoKSOAuV


question:
hGyDyQYdxCCuD, BQiFOyQYdxel
answer:
yQYdx


question:
UGEKVJEFiIsnGpFNwgPpW, elRcDFiIsnGpZovopv
answer:

FiIsnGp