function Main(input) {
  const data = input.trim().split("\n")
  const X = parseInt(data[0]), Y = parseInt(data[1]), L = parseInt(data[2])
  let count = 0
  count += X ? 1 : 0
  if (Y < 0) {
    count += count ? 1 : 2
  }
  count += Math.ceil(Math.abs(X) / L)
  count += Math.ceil(Math.abs(Y) / L)
  console.log(count)
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"))