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

Q: bUHPpvVtFQNSpUdg, zggEFoKBHPpvVtFQNHXsc

A: HPpvVtFQN
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Q: TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK

A: YjBCeUpy
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Q: rnHbuXYL, OFHbuXCBLb

A:
HbuX
****