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

[Q]: spGRUmIYuGl, qkqRUmItqU
[A]: RUmI


[Q]: fAsWQxuyBevvLogrSrgg, tmdBEUxuyBevvLogXjiMCbh
[A]: xuyBevvLog


[Q]: zzEhnt, sYEhtc
[A]:
Eh