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

int main(void){

  int x,y,l;
  int a=0,b=0;
  int n=0;
  scanf("%d",&x);
  scanf("%d",&y);
  scanf("%d",&l);
  int xl = l;
  int yl = l;
  while(a != x || b != y){
    if(x < 0 && xl > 0){
      xl *= -1;
    }
    else if( a != x){
      a += (abs(x-a)<l)?(x-a):xl;
    }

    else if(y < 0 && yl > 0){
      n++;
      yl *= -1;
    }
    else if(b != y){
      b += (abs(y-b)<l)?(y-b):yl;
    }
    n++;
  }
  printf("%d\n",n);
  return 0;
}