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

[EX Q]: ahPbomjSH, rBbomynK
[EX A]: bom

[EX Q]: SJIkEibGrqcrOBgGjYjJc, EervOGrqcrOBgGJZyx
[EX A]: GrqcrOBgG

[EX Q]: LJTPJUNciVnQOlOpnNq, PbFGkciVnQOlOpnBXySAnBP
[EX A]:
ciVnQOlOpn