instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
mvIvSzMtYsfVLdaGEmef, wnzMtYsfVLdaKm
answer:
zMtYsfVLda


question:
eMDNXl, ZZDNAa
answer:
DN


question:
FuiTWiEiFfdprAonJCH, ZcoIWiEiFfdpmwe
answer:

WiEiFfdp