#include <iostream>
#include <list>
#include <vector>
#include <string>
#include <stdio.h>
#include <stdint.h>
using namespace std;

using uint = unsigned int;
using ll = long long;

inline ll CountStep( const ll& D , const ll& L ) { return D >= 0 ? D / L + ( D % L == 0 ? 0 : 1 ) : CountStep( - D , L );}

int main()
{

  ll X;
  cin >> X;
  ll Y;
  cin >> Y;
  ll L;
  cin >> L;

  ll step;
  
  if( Y >= 0 ){

    step = CountStep( Y , L ) + ( X == 0 ? 0 : 1 + CountStep( X , L ) );

  } else {

    step = 1 + CountStep( X , L ) + 1 + CountStep( Y , L );

  }

  cout << step << endl;
  return 0;

}