#include<stdio.h>
#include<algorithm>
using namespace std;
int main(){
	int a,b,c;
	scanf("%d%d%d",&a,&b,&c);
	int ret=0;
	if(b<0)ret+=2;
	else if(a)ret++;
	if(b<0)b=-b;
	if(a<0)a=-a;
	ret+=(a+c-1)/c+(b+c-1)/c;
	printf("%d\n",ret);
}