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

int main(){

  int x, y, l, cnt = 0;

  cin >> x >> y >> l;

  if(x) cnt = 1;
  if(y < 0) cnt = 2;

  x = abs(x), y = abs(y);
  
  cout << cnt + (x + l - 1) / l + (y + l - 1) / l << endl;

}