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

Q: spGRUmIYuGl, qkqRUmItqU

A: RUmI
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Q: ocjsZZfSBBopDtgWUT, rWmgzsZZfSBBoGWQ

A: sZZfSBBo
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Q: yhhzISsXKEbA, KlPrazISsXKzmrVBG

A:
zISsXK
****