#include <stdio.h>
int main()
{
	int X,Y,L;
	scanf("%d%d%d",&X,&Y,&L);
	if(X==0){
		if(Y==0){
		printf("0\n");
		}
		else if(Y>0){
			printf("%d\n",(Y-1)/L+1);
		}
		else{
			printf("%d\n",(-Y-1)/L+3);
		}
	}
	else{
		if(Y==0){
			printf("%d\n",(X>0?X-1:-X-1)/L+2);
		}
		else if(Y>0){
			printf("%d\n",(X>0?X-1:-X-1)/L+(Y-1)/L+3);
		}
		else{
			printf("%d\n",(X>0?X-1:-X-1)/L+(-Y-1)/L+4);			
		}
	}
	return 0;
}