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

[Q]: vSFxjd, AHFxpi
[A]: Fx


[Q]: aiqZheFuLtXAGRCGNBTAX, ssnVdztXAGRCGNBTIqmSJLZcy
[A]: tXAGRCGNBT


[Q]: UVWxiJwJrdjNKyDnH, lnRJwJrdjNKyJRQAVP
[A]:
JwJrdjNKy