#include <stdio.h>
#include <math.h>

int main(void)
{
	int x,y,l,s=0;
	scanf("%d%d%d",&x,&y,&l);
	if(y<0)s+=2;
	if(x!=0&&y>=0)s++;
	s+=fabs(x)/l;
	s+=fabs(y)/l;
	if((int)fabs(x)%l)s++;
	if((int)fabs(y)%l)s++;
	printf("%d",s);
	return 0;
}