#include <bits/stdc++.h>

using namespace std;

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