# a‿b Sub x: the b-length subarray starting at a
Sub ⇐ {a‿b𝕊𝕩:b↑a↓𝕩}

# e Split xs: split xs on occurrences of e (default 0)
Split ⇐ {(⊏ ∾ 1⊸↓¨∘(1⊸↓)) Sub⟜𝕩¨ (» ⋈¨ ⊢-») /𝕨=𝕩∾(𝕨⊣⟜0↩)}

Day1 ⇐ (⊑ ⋈ (+´3⊸↑))∘(∨+´¨)∘Split∘(•BQN⎊0¨)∘•FLines

Day2 ⇐ {
  B ← ⊣ (A ← {1+𝕩+3×3|1+𝕩-𝕨}) {3|𝕨+𝕩-1}
  +´˘⍉ (A≍B)´∘{a‿s‿b:⟨a-'A',b-'X'⟩}˘ >•FLines 𝕩
}
•Show Day2 ⊑•args

# day 3 maybe later