#include <iostream>
using namespace std;

int main()
{
	int X, Y, K;
	cin >> X >> Y >> K;

	cout << ((Y >= 0) ? ((X == 0) ? 0 : 1) : 2) + (abs(X) - 1 + K) / K + (abs(Y) - 1 + K) / K << endl;

	return 0;
}