#include <stdio.h>
#include <algorithm>
#include <deque>
using namespace std;
using ll = long long;

int main() {
	int x, y, l;
	scanf("%d %d %d", &y, &x, &l);

	int opes = 0;
	opes += (max(0, x) + l - 1) / l;
	opes += x < 0 || y != 0;
	opes += abs(y) / l;
	opes += x < 0;
	opes += (max(0, -x) + l - 1) / l;
	printf("%d\n", opes);
}