#include<iostream>
#include<math.h>

using namespace std;

int main(){

  double x,y,z;
  int to=0;
  cin >> x >> y >> z;

  if(x==0&& y>=0)
  to += ceil(abs(y)/z);
  else if(x!=0&&y>=0)
  to += ceil(abs(y)/z)+1+ceil(abs(x)/z);
  else
  to += 2+ceil(abs(y)/z)+ceil(abs(x)/z);


  cout << to <<endl;
  return 0;
}