instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
jJSSBmflUyrEMLjSycA, YkmujkSSBmflUyrKKJZ
answer:
SSBmflUyr


question:
lsNwypFwhKP, diEfLwypFwEKqCN
answer:
wypFw


question:
AfOOHwkyyH, jYEOHwkYxdc
answer:

OHwk