In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
--------
Question: CxosNa, ikosdx

Answer: os


Question: aWshKwEuYBBdSwIAyXw, wfVuYBBdSwIAseTxR

Answer: uYBBdSwIA


Question: WDtFnE, VutFBR

Answer:
tF