#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <cmath>

using namespace std;

int main() {
	int x, y, l;

	cin >> x >> y >> l;
	int count = 0;

	count += ceil(1.0 * abs(x) / l);
	count += ceil(1.0 * abs(y) / l);
	if (y < 0) {
		count += 2;
	} else if (x != 0) {
		count++;
	}
	cout << count << endl;
	return 0;
}