instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
XmiLktrUjJDOCJ, UIKrUjJDOQsR
answer:
rUjJDO


question:
vSFxjd, AHFxpi
answer:
Fx


question:
CvWfXHegyGXIAyYUE, kMznmUhUXHegyGXIARBySBMyr
answer:

XHegyGXIA