instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
RpaZAvSnEBgGapIPQgw, wcwYsXvSnEBgGapIwoIWROB
answer:
vSnEBgGapI


question:
rCFrfkmXbSHK, mztfkmXwez
answer:
fkmX


question:
pAJDvWtvLXEY, SUhClKJDvWtvwuIl
answer:

JDvWtv