o ← @‿'A'‿@‿'a'‿@ ⋄ m ← 5⥊↕2 ⋄ p ← m⊏∞‿26
Rot ← {i←⊑"A[a{"⍋𝕩 ⋄ i⊑o+p|(𝕨×m)+𝕩-o}⎉0