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

using namespace std;

int main(){

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

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


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