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

Ex Input:
libDFDxIgRiglWfxMVRr, yMltDxIgRiglpms

Ex Output:
DxIgRigl


Ex Input:
VTwtMVKmrRvL, WLoVtWtMVKmrDCke

Ex Output:
tMVKmr


Ex Input:
TQdVmxckWqM, sBwVmxckpu

Ex Output:

Vmxck