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

[EX Q]: iupYjFXrrMqWzJSLUSwmEukHc, hqajjWrrMqWzJSLnF
[EX A]: rrMqWzJSL

[EX Q]: sCMyALRSDknURKqZDlqFf, oEIfHyALRSDknUrnMebev
[EX A]: yALRSDknU

[EX Q]: IEYaqHFWbQzqKF, WuMYYaqHFWfde
[EX A]:
YaqHFW