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

[Q]: HaIPcFXLhYDp, AdIPcFXtJdRE
[A]: IPcFX


[Q]: rCFrfkmXbSHK, mztfkmXwez
[A]: fkmX


[Q]: qjstYmX, RxxstYEp
[A]:
stY