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

kvutZfcPKzHE, kTKutZfcPTGmU
utZfcP

libDFDxIgRiglWfxMVRr, yMltDxIgRiglpms
DxIgRigl

iaXeqfIrYKxPJRXxfSm, rIYKxPJRXxfsjVsqe

YKxPJRXxf