instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
XWKEpwGRkfCFZGOyZQOoypx, lhQkmVqeRkfCFZGOyugPLqs
answer:
RkfCFZGOy


question:
MSzHyOuaJILkeY, eUibEHoHyOuaJIhfvXy
answer:
HyOuaJI


question:
GiQQFumAhPSEcrgJJytHsEy, NHXrMumAhPSEcrgoPgK
answer:

umAhPSEcrg