#include<iostream>
#include<string>
#include<algorithm>
#include<utility>
#include<cmath>
using namespace std;
int main(void){
	int x,y,l,counter=0;
	cin>>x>>y>>l;

	if(y<0)counter+=2;
	else if(y>=0&&x!=0)counter++;

	y=abs(y);
	counter+=y/l;
	if(y%l!=0)counter++;


	x=abs(x);
	counter+=x/l;
	if(x%l!=0)counter++;


	cout<<counter<<endl;
}