#include <iostream>
using namespace std;
int main(void) {
	int x, y, l;
	cin >> x >> y >> l;
	int cnt = 0;
	if (x != 0) cnt = 1;
	if (y < 0) cnt = 2;
	x = abs(x), y = abs(y);
	cnt += (x + l - 1) / l;
	cnt += (y + l - 1) / l;
	cout << cnt << endl;
	return 0;
}