#include <bits/stdc++.h>
using namespace std;

int main() 
{
  int x, y, l;
  cin >> x >> y >> l;
  int count = 0;
  if(y >= 0)
  {
      int a = (y+l-1)/l;
      count += a;
  }
  if(x != 0)
  {
      int a = (abs(x)+l-1)/l;
      count +=(a+1);
      if(y < 0) count++;
  }
  else
  {
      if(y < 0) count += 2;
  }
  if(y < 0)
  {
      int a = (abs(y)+l-1)/l;
      count += a;
  }
  cout << count;

}