1 2 3 4 5 6
CheckOrder ⇐ ⍸≠∘∧ ⍝ Tests CheckOrder 5 2 4 3 1 ⍝ 0 2 3 4 CheckOrder 1 2 1 1 3 ⍝ 1 3 CheckOrder 3 1 3 2 3 ⍝ 0 1 3