instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
dsngGP, KvnglB
answer:
ng


question:
sCMyALRSDknURKqZDlqFf, oEIfHyALRSDknUrnMebev
answer:
yALRSDknU


question:
NaCAvAdfZVuO, fvPvAdfkS
answer:

vAdf