#include <bits/stdc++.h>
using namespace std;

signed main(){
  int X, Y, L; cin >> X >> Y >> L;
  cout << ( Y < 0 ) + ( X == 0 and Y < 0 ) + ( X != 0 ) + ( abs( X ) + L - 1 ) / L + ( abs( Y ) + L - 1 ) / L << endl;
  return 0;
}