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

Example Input: edjRAatlaiCmWkpqMh, qDZYVWCDTRAatlaiCmYH
Example Output: RAatlaiCm

Example Input: sCMyALRSDknURKqZDlqFf, oEIfHyALRSDknUrnMebev
Example Output: yALRSDknU

Example Input: ujrkcGeGWKD, HtKScGeGgYOH
Example Output:
cGeG