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

int main(void){
	int x,y,l;
	double tmp,ans;
	scanf("%d%d%d",&x,&y,&l);
	
	tmp = abs(x)/(double)l;
	ans += ceil(tmp);
	tmp = abs(y)/(double)l;
	ans += ceil(tmp);
	
	if(x!=0 && y>0) ans++;
	if(y<0)ans++;
	
	printf("%.0f\n",ans);
	return 0;
}