#include<stdio.h>
#define abs(a) ((a)<0?-(a):(a))
int main(){
	long x,y,l,s=0;
	scanf("%ld%ld%ld",&x,&y,&l);
	if(y<0) s+=2;
	else if(x!=0) s++;
	x=abs(x);
	y=abs(y);
	s+=(x+l-1)/l+(y+l-1)/l;
	printf("%ld\n",s);
	return 0;
}