#include<stdio.h>
#include<stdlib.h>

int main(void){

  long int x,y,l;
  long int n=0;
  scanf("%ld",&x);
  scanf("%ld",&y);
  scanf("%ld",&l);
  if(x < 0){
    n++;
  }
  if( x != 0){
    n += (abs(x)-(abs(x)%l))/l;
    n += (x%l)?1:0;
  }

  if(y < 0){
    n+=2;
  }
  if(y != 0){
    n += (abs(y)-(abs(y)%l))/l;
    n += (y%l)?1:0;
  }

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