farey←{{⍵[⍋⍵]}∪∊{(0,⍳⍵)÷⍵}¨⍳⍵}
fract←{1∧(0(⍵=0)+⊂⍵)*1 ¯1}
print←{{(⍕⍺),'/',(⍕⍵),' '}⌿↑fract farey ⍵}