fun F ← int by int n, int x, int y
  if n æ 0
    return x + y
  else if y æ 0
    return x
  end
  return F(n - 1, F(n, x, y - 1), F(n, x, y - 1) + y)
end
writeLine("F(1, 3, 3) ← ", F(1, 3, 3))
writeLine("F(2, 1, 1) ← ", F(2, 1, 1))
writeLine("F(3, 1, 1) ← ", F(3, 1, 1))
writeLine("F(2, 2, 1) ← ", F(2, 2, 1))