#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int main(){
	int x, y, l;
	int countx = 0, county = 0;
	cin >> x >> y >> l;
	if (x != 0 && y != 0)countx=countx+2;
	else if (x != 0 || y != 0)countx--;
	else countx--, county--;
	while (x > 0){
		x = abs(x) - l;
		countx++;
	}
	while (y > 0){
		y = abs(y) - l;
		county++;
	}
	cout << countx + county << endl;

	return 0;
}