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

Example Input: oWwqraAz, uxTqraonu
Example Output: qra

Example Input: elloYaejTczBiiNOU, XoCPzloYaejTcXYtKODL
Example Output: loYaejTc

Example Input: fQZmUoijJmKOduoyviwhp, VRtmazsGqUjJmKOduoyvvMR
Example Output:
jJmKOduoyv