1  &fras ⊣ &args
 2  
 3  ⊜∘⊸≠@\n
 4  
 5  ⊜□+1⊃⍜♭⊛(⇡△)
 6  
 7  A ← /+≡(/+¬∊:+⊂⟜¯⋯1_2¤)⟜¤
 8  B ← (
 9    ◴♭₂⊞+-1×2⋯⇡4⟜¤×2
10    /+≡(↥⊃(◿2/+|×2/×⧈≠)∊:+-1×2⍜↘₂⇌⋯⇡4¤)
11  )
12  
13  ∩(/+×)⊙,≡◇⊃B A ⟜≡◇⧻