You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

PPdQTlHHTJEe, DydQTlHHVnmlLu
Solution: dQTlHH
Why? Here, 'dQTlHH' is the longest common substring in both the input strings 'PPdQTlHHTJEe' and 'DydQTlHHVnmlLu'.

New input: aIZIsqL, wxSZIsEnO
Solution:
ZIs