d4469b4b ​

input = #0
output = fill 3v (fill 3h grey) |> fold (λr. rect (r, black)) #1
(OList OList Color, UList (VInt, HInt, VInt, HInt))
([[red, black, black, black, black], [black, red, black, black, red], [red, black, black, red, black], [black, black, black, red, red], [black, black, red, red, black]], {(2v, 3h, 3v, 3h), (2v, 1h, 3v, 1h)})
([[black, black, black, black, black], [black, black, blue, blue, blue], [black, blue, black, blue, blue], [black, blue, black, blue, black], [black, black, black, black, blue]], {(3v, 3h, 3v, 3h), (3v, 1h, 3v, 1h), (1v, 3h, 1v, 3h), (1v, 1h, 1v, 1h)})
([[green, black, black, black, black], [black, black, black, green, green], [black, green, green, black, black], [black, green, black, green, black], [green, black, green, green, black]], {(1v, 1h, 2v, 2h)})
([[blue, black, blue, black, black], [blue, black, black, blue, blue], [blue, blue, black, blue, black], [black, blue, black, blue, black], [blue, black, black, black, blue]], {(3v, 3h, 3v, 3h), (3v, 1h, 3v, 1h), (1v, 3h, 1v, 3h), (1v, 1h, 1v, 1h)})
([[red, black, red, black, red], [red, black, black, black, red], [red, red, black, black, black], [red, black, black, red, red], [red, red, red, black, red]], {(2v, 3h, 3v, 3h), (2v, 1h, 3v, 1h)})
([[black, red, black, red, black], [black, red, red, red, black], [black, red, red, black, red], [red, red, red, black, black], [black, black, red, black, red]], {(2v, 3h, 3v, 3h), (2v, 1h, 3v, 1h)})
([[black, green, black, green, black], [green, green, black, black, black], [black, green, black, black, black], [black, black, green, black, black], [green, green, green, black, black]], {(1v, 1h, 2v, 2h)})
([[blue, blue, blue, blue, black], [black, black, blue, black, blue], [black, blue, black, black, black], [black, blue, black, black, blue], [black, black, blue, black, black]], ?)
([[black, green, black, green, green], [black, black, green, black, black], [green, black, black, black, black], [black, black, green, black, green], [black, black, black, black, green]], ?)