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

Answer: fkmX


Question: libDFDxIgRiglWfxMVRr, yMltDxIgRiglpms

Answer: DxIgRigl


Question: XKIkNcaleI, jJXIkNcjtT

Answer:
IkNc