#include <iostream>
#include <algorithm>
using namespace std;
int main(){
  double x,y,l;
  cin>>x;
  cin>>y;
  cin>>l;
  int a,b,c;
  c=0;
  if(x!=0){
    c++;
  }
  if(x!=0 && y<0){
    c++;
  } else if (x==0 && y<0){
    c+=2;
  }
  a=ceil(abs(x)/l);
  b=ceil(abs(y)/l);
  c+=a;
  c+=b;
  cout<<c<<endl;
  return 0;
}