#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int x, y, l;
  cin >> x >> y >> l;
  int ans = (y < 0 ? 2 : x == 0 ? 0 : 1);
  ans += (abs(x) + l - 1) / l;
  ans += (abs(y) + l - 1) / l;
  cout << ans << endl;
  return 0;
}