go =>
   List = [455,999,1990,1999,2000,2001,2008,2009,2010,2011,2012,1666,3456,3888,4000],
   foreach(Val in List)
      printf("%4d: %w\n", Val, roman_encode(Val))
   end,
   nl.

roman_encode(Val) = Res =>
  if Val <= 0 then
     Res := -1
  else
     Arabic = [1000, 900, 500, 400,  100, 90,  50, 40,  10,  9,  5,  4,   1],
     Roman  = ["M", "CM", "D", "CD", "C", "XC","L","XL","X","IX","V","IV","I"],
     Res = "",
     foreach(I in 1..Arabic.length)
        while(Val >= Arabic[I])
           Res := Res ++ Roman[I],
           Val := Val - Arabic[I]
        end
     end
  end.