#include <iostream>

using namespace std;

int action (int num, int l)
{
  int count = 0;

  if (num >= l) {
    count += num/l;
    num = num % l;
  }
  count += num;

  return count;
}

int main ()
{
  int x, y, l;
  cin >> x >> y >> l;
  if (x < 0) x *= -1;
    if (y < 0) y *= -1;
    int count = 0;
    if (y) count = 1;
    else if (!y) count = 2;
    count += action(y,l)+action(x,l);
  
  cout << count << endl;
  return 0;
}