1  &fras ⊣ &args
 2  
 3  ⊜≡⋕≠@\n.
 4  
 5  Neis  ← [∩¯,,⊸⇌⇡2]
 6  Valid ← /××≥0⟜>⊙△
 7  
 8  Line ← +⍉⬚0≡⍜⌵⇡⊃-¤
 9  
10  Next ← (
11    ▽≠0◿2⊸+:⇡4°⊂
12    ♭₂⊞⊂⊙⊃⋅⋅∘⊙.
13    ⊙⟜:
14    ≡(⟜(+×⊏⊙Neis)°⊟)⊙¤
15    ∩▽,⊙(:⟜≡Valid|¤)
16    ⊙⟜(≡(/+⊡Line)⊙∩¤)
17    :⍉⊂⊙⍉
18  )
19  
20  Solve ← ◌path(Next|≍+1⊙△↘1)∞_0_0 :⍜-⇡⊙(+1)
21  
22  ⊃(Solve 4 10|Solve 1 3)