⎕IO←0 p←'L'=↑⊃⎕NGET'input'1 s←{(1=1 1⌷⍵)∧∧/2≠,⍵:2 ⋄ (2=1 1⌷⍵)∧4<+/2=,⍵:1 ⋄ 1:1 1⌷⍵}⌺3 3 +/,2=(s⍣≡)p ⍝ Part 1