#include<stdio.h>

int main(void){
	int x,y,l,r=0;
	scanf("%d%d%d",&x,&y,&l);
	if(y < 0){y*=-1;r+=2;}
	if(x < 0){x*=-1;}
	if(x != 0){r++;}
	if(x%l){r+=(1+(x/l));}else{r+=(x/l);}
	if(y%l){r+=(1+(y/l));}else{r+=(y/l);}
	printf("%d\n",r);
	return 0;
}