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

int main() {
  long long x, y, l;
  cin >> x >> y >> l;
  long long ans=0;

  if (x != 0) {
    if (y >= 0) ans++;
    if (y < 0) ans+=2;
  }

  ans += abs(x)/l;
  if (abs(x)%l != 0) ans++;

  ans += abs(y)/l;
  if (abs(y)%l != 0) ans++;

  cout << ans << endl;

  return 0;
}