#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;
	x=abs(x);
	y=abs(y);

	if(x!=0&&y!=0)counter++;

	counter+=x/l;
	if(x%l!=0)counter++;
	counter+=y/l;
	if(y%l!=0)counter++;
	cout<<counter<<endl;
}