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

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