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

Input: Consider Input: GHdeqnuYnQ, zzQeqnutAZ

Output: eqnu

Input: Consider Input: cfvqbAUpWEmhCSFaUvGrYVNGeUiRP, hAxWMEmhCSFaUvGLBLmdTxhy

Output: EmhCSFaUvG

Input: Consider Input: EdSSgNhjyID, xfSgNhRzy
Output: SgNh