#include<stdio.h>
#include<math.h>

int main()
{
  long int x;
  long int y;
  long int l;
  int count=0;
  long int tmp;
  double k;
  scanf("%ld %ld %ld",&x,&y,&l);


  if(x>0 && y>0){
    count++;
  }
  else if(x>0 && y<=0){
    count+=2;
  }
  else if(x<0 && y>=0){
    count++;
  }
  else{
    count+=2;
  }


  //距離の計算
  count += (int)ceil(fabs((double)y)/l);
  count += (int)ceil(fabs((double)x)/l);


  printf("%d\n",count);

  return 0;
}