instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
SUgXyznbUQRpiLUTlRb, jlnwLTnbUQRpioUFyJ
answer:
nbUQRpi


question:
zqwhMdAdXQfQCAmVNaYZm, toYMIwQeadAdXQfQCAmLyheFOv
answer:
dAdXQfQCAm


question:
GFrSQnKstBZiiMUyU, yJESQnKstBZyFsxRJa
answer:

SQnKstBZ