#include<iostream>
#include<algorithm>
#include<stdio.h>
#include<stdlib.h>
#include<vector>
#include<string>
#include<sstream>
#include<math.h>
using namespace std;


int main(){

  long long int x,y,l;
  cin >> x;
  cin >> y;
  cin >> l;

  int cnt = 0;
  if(y < 0) cnt++;
  if(x != 0) cnt++;

  if(y != 0){
    if( y%l == 0 ){
      cnt += abs(y/l);
    }else{
      cnt += abs(y/l)+1;
    }
  }

  if( x != 0 ){
    if( x%l == 0 ){
      cnt += abs(x/l);
    }else{
      cnt += abs(x/l)+1;
    }
  }

  cout << cnt << endl;

  return 0;
}