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