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

Q: libDFDxIgRiglWfxMVRr, yMltDxIgRiglpms

A: DxIgRigl
****
Q: yKtQOhYvrJVH, HQsTQOhYvPP

A: QOhYv
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Q: ZQMQHxN, ZmdMQHpx

A:
MQH
****