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

int main(){
	int x,y,l;
	int inst;
	scanf("%d%d%d",&x,&y,&l);
	
	if(y<0){
		inst=2;//y+ -> x+ or x- -> y-
	}else if(y>=0 && x==0){
		inst=0;//y+
	}else{
		inst=1;//y+ -> x+ or x-
	}
	
	inst += (int)ceil((double)abs(x)/(double)l);
	inst += (int)ceil((double)abs(y)/(double)l);
		
	printf("%d\n",inst);
	
	return 0;
}