#include<stdio.h>
int main(){
	int X,Y,L,i,j,ans=0;
	scanf("%d%d%d",&X,&Y,&L);
	if(X<0)
		X=-X;
	if(Y<0)
		Y=-Y;
	if(X%L==0)
		ans=ans+X/L;
	else
		ans=ans+X/L+1;
	
	if(Y%L==0)
		ans=ans+Y/L;
	else
		ans=ans+Y/L+1;
	
	if(X!=0)
		ans++;
/*	if(Y!=0)
		ans++;
*/	
	printf("%d\n",ans);
	return 0;
}