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

Input: Consider Input: IKrQfT, crrQRg

Output: rQ


Input: Consider Input: KTAFonizDqCVvucpJWrItdw, rfFonizDqCVvYbGhb

Output: FonizDqCVv


Input: Consider Input: qQxXSuIaf, wJwXSuhKz


Output: XSu