#include <stdio.h>

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