instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
kvutZfcPKzHE, kTKutZfcPTGmU
answer:
utZfcP


question:
rvLoiycpZw, idcvoiycpcLyD
answer:
oiycp


question:
NoArpDIGxasZINYWLVVDNMI, MclVDIGxasZINSTZZcaL
answer:

DIGxasZIN