#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#define REP(i,n) for(int i=0;i<(n);++i)
#define SORT(a) sort((a).begin(),(a).end())
#define PB push_back
using namespace std;
typedef vector<int> VI;
typedef queue<int> QI;

int main(){
  int X, Y, L;
  cin >> X >> Y >> L;
  int r;
  if(X == 0){
    r = 0;
    if(Y != 0){
      if(Y < 0){
        r = 2;
        Y = -Y;
      }
      r += (Y - 1) / L + 1; 
    }
  }else{
    if(X < 0){ X = -X; }
    r = 2 + (Y == 0 ? 0 : (Y - 1) / L + 1) + (X - 1) / L;
  }
  cout << r << endl;
}