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

[EX Q]: iUtNuU, iKtNWk
[EX A]: tN

[EX Q]: jAinxmaQUrmu, jqeEnxmaQUrWlrEqW
[EX A]: nxmaQUr

[EX Q]: tFxdjJrOYxbbvLvTLVGEvpwO, gnyCITmxbbvLvTLVvN
[EX A]:
xbbvLvTLV