instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OXdSmcKG, XbDdSmJl
answer:
dSm

question:
oHoJrr, YAoJSq
answer:
oJ

question:
ixyjFRhXjAnScOh, HPnBRhXjAnScdh
answer:
RhXjAnSc