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

using namespace std;
//namaega 184

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