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

using namespace std;

int main(){

  int x,y,z,to=0;
  cin >> x >> y >> z;
  x = abs(x);

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


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