In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Example Input: OVVkkdeHoFlyNROyCP, zFVUJbvkkdeHoFlysF
Example Output: kkdeHoFly

Example Input: eFUexDIFlaPDUwrOb, mTvkKGUxDIFlaPDUwxGVpnIwbi
Example Output: xDIFlaPDUw

Example Input: HKqkanGxVFaAoxYOuNn, WOqFDUoLoxVFaAoxYOucqCyMOjXt
Example Output:
xVFaAoxYOu