#include <stdio.h>

int main(void) {
  int x,y,l,count = 0,robX = 0,robY = 0;
  scanf("%d",&x); scanf("%d",&y); scanf("%d",&l);

  if(y >= 0){
    while(1){
      if(robY >= y)break;
      robY += l;
      count++;
    }
    if(x != 0)count++;
    if(x < 0)x *= -1;
    while(1){
      if(robX >= x)break;
      robX += l;
      count++;
    }
  }

  else{
    if(x < 0)x *= -1;
    count++;
    while(1){
      if(robX >= x)break;
      robX += l;
      count++;
    }
    count++;
    while(1){
      if(robY <= y)break;
      robY -= l;
      count++;
    }
  }

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