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

Input: Consider Input: HXYkGv, GCYksu

Output: Yk


Input: Consider Input: XYnCjAWPHHJ, gmCjAWPHpmwVsm

Output: CjAWPH


Input: Consider Input: MFMADQccYBEVbzpGKsT, lhQccYBEVQkSu


Output: QccYBEV