#include<iostream>
#include<complex>
#include<cmath>
using namespace std;

int Going(int x, int l){
  return (int)ceil( abs((double)x / l) );
  
}

int main(){
  int x, y, l;
  cin >>x>>y>>l;

  int c = 0;

  if(x == 0 && y == 0){
    cout << 0 << endl;
    return 0;
  }

  if(y>=0){
    c += Going(y, l);

    if(x!=0){
      c++;
      c += Going(x, l);
    }
    
  }else{
    //y < 0
    c++; //Turn
    c += Going(x, l);

    c++; // Turn
    c += Going(y, l);
  }

  cout << c << endl;
  
  return 0;
}