#include <bits/stdc++.h>
using namespace std;
int main(){
  int X;
  cin >> X;
  int Y;
  cin >> Y;
  int L;
  cin >> L;
  int tmp = (abs(X) + L - 1) / L + (abs(Y) + L - 1);
  if (X == 0){
    if (Y < 0){
      cout << tmp + 2 << endl;
    } else {
      cout << tmp << endl;
    }
  } else {
    if (Y < 0){
      cout << tmp + 2 << endl;
    } else {
      cout << tmp + 1 << endl;
    }
  }
}