inputs = STDIN.readlines.map(&:chomp)
x = inputs[0].to_i
y = inputs[1].to_i
l = inputs[2].to_i

def operations(x, y, l)
  c = x.abs / l + (x % l == 0 ? 0 : 1) +
      y.abs / l + (y % l == 0 ? 0 : 1)
  c + case
      when x == 0 && y >= 0
        0
      when y >= 0
        1
      else
        2
      end
end

puts operations(x, y, l)