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

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

  //(x,y)まで移動
  if(y<0){
    count++;
    y = -1*y;//負ならば正にする
  }
  k = (double)y/l;
  count += (int)ceil(k);

  if(x<0){
    count++;
    x = -1*x;
  }
  k = (double)x/l;
  count += (int)ceil(k);

  printf("%d",count);
  return 0;
}