#include <stdio.h>

int calc(int a, int b){
	int p = 0;
	while(a > 0){
		a -= b;
		p++;
	}
	return p;
}

int main(void){
	int x, y, l;
	int cnt = 0;
	
	scanf("%d%d%d", &x, &y, &l);
	
	if(y > 0){
		cnt = calc(y, l);
	}else if(y < 0){
		y = abs(y);
		cnt = calc(y, l) + 1;
	}
	if(x > 0){
		cnt += calc(x, l) + 1;
	}else if(x < 0){
		x = abs(x);
		cnt += calc(x, l) + 1;
	}
	
	printf("%d", cnt);
	
	return 0;
}