#include<stdio.h>	
#include<stdlib.h>

int main()
{
	int x, y, l;
	int total;
	int X, Y;
	int ycount, xcount;
	scanf("%d%d%d", &x, &y, &l);

	X = abs(x);
	Y = abs(y);

	if (Y%l == 0) ycount = Y / l;
	else ycount = Y / l + 1;
	
	if (X%l == 0) xcount = X / l;
	else xcount = X / l + 1;


	if (y >= 0)
		if (x == 0) total = ycount + xcount;
		else total = ycount + 1 +  xcount;
	else
		total = 1 + xcount + 1 + ycount;


	printf("%d\n", total);

	return 0;
}