#include <cmath>
#include <iostream>

using namespace std;

int main(int argc, const char* argv[])
{
	int X, Y, L;
	cin >> X >> Y >> L;
	int cnt = 0;
	if (X != 0 && Y >= 0) cnt++;
	if (Y < 0) cnt += 2;
	cnt += (abs(X) + L - 1) / L;
	cnt += (abs(Y) + L - 1) / L;
	cout << cnt << endl;
	return 0;
}