#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;


int main(){
  int X, Y, L;

  cin >> X >> Y >> L;
  
  int ret = 0;
  if(Y<0){
    ret += 2;
    if(X==0) ret--;
  }
  else{
    ret += 1;
    if(X==0) ret--;
  }
  Y = abs(Y);
  X = abs(X);
  ret += (Y/L+(Y%L!=0)) + (X/L+(X%L!=0));
  
  cout << ret << endl;
  
  return 0;
}