function Main(input: string) {
  const inputNumbers = input.split("\n");
  const X = Number(inputNumbers[0]);
  const Y = Number(inputNumbers[1]);
  const L = Number(inputNumbers[2]);
  let numCommand = 0;

  if(Y >= 0){
    numCommand += Math.round(Y/L);
    if(X != 0){
      numCommand++;
      numCommand += Math.round(X/L);
    }
  } else {
    numCommand++;
    numCommand += Math.round(X/L);
    numCommand++;
    numCommand += Math.round(Y/L);
  }
  console.log(numCommand);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));