#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
 
using namespace std;
 
#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define clr(a, b) memset((a), (b) ,sizeof(a))
 
#define MOD 1000000007

int main(){
  int x,y,L;
  cin >> x;
  cin >> y;
  cin >> L;
  if(x == 0 && y == 0){
    cout << 0 << endl;
    return 0;
  }
  if(x == 0){
    if(y > 0){
      int c = 0;
      int l = 0;
      for(;;){
        l+=L;
        c++;
        if(l>=y){
          cout << c << endl;
          return 0;
        }
      }
    }
    else{
      int c = 0;
      int l = 0;
      for(;;){
        l+=L;
        c++;
        if(l>=-y){
          cout << c+2 << endl;
          return 0;
        }
      }
    }
  }
  if(y == 0){
    int c = 0;
    int l = 0;
    for(;;){
      l+=L;
      c++;
      if(l>=abs(x)){
        cout << c+1 << endl;
        return 0;
      }
    }
  }
  if(y > 0){
    x = abs(x);
    int c = 0;
    int l = 0;
    for(;;){
      if(x > 0){
        x -= min(L,x);
        c++;
      }
      else if(y > 0){
        y -= min(L,y);
        c++;
      }
      else{
        cout << c+1 << endl;
        return 0;
      }
    }
  }
  if(y < 0){
    x = abs(x);
    y = abs(y);
    int c = 0;
    int l = 0;
    for(;;){
      if(x > 0){
        x -= min(L,x);
        c++;
      }
      else if(y > 0){
        y -= min(L,y);
        c++;
      }
      else{
        cout << c+2 << endl;
        return 0;
      }
    }
  }

  return 0;
}