#include<stdio.h>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <algorithm>
#include <sstream>
#include <iostream>
#include <string>

using namespace std;

int main() {

	int X, Y, L;
	cin >> X >> Y >> L;

	int  cnt = 0;

	if (Y < 0) cnt++;
	if (X != 0) cnt++;
	
	/*
	cout << "dy: " << (abs(Y) + L - 1) << endl;
	cout << "dx: " << (abs(X) + L - 1) << endl;
	*/
	
	cnt += (abs(Y) + L-1 ) / L + (abs(X) + L - 1) / L;

	cout << cnt << endl;

	return 0;
}