instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
OVZxWYzAAxG, rStOxWYzJeoC
answer:
xWYz


question:
RpaZAvSnEBgGapIPQgw, wcwYsXvSnEBgGapIwoIWROB
answer:
vSnEBgGapI


question:
VSIbLRw, bFGIbLoop
answer:

IbL