#include <iostream>

using namespace std;

int main() {
	int x, y, l;
	int count = 0;
	cin >> x >> y >> l;

	if (y >= 0) {
		while (y > 0) {
			y -= l;
			count++;
		}
		if (x != 0) {
			count++;
			x = (x >= 0) ? x : (-x);
			while (x > 0) {
				x -= l;
				count++;
			}
		}
	}
	else {
		count++;
		x = (x >= 0) ? x : (-x);
		while (x > 0) {
			x -= l;
			count++;
		}
		count++;
		y = (-y);
		while (y > 0) {
			y -= l;
			count++;
		}
	}

	cout << count << endl;
	return 0;
}