#include <stdio.h>

long absolute(long n)
{
	if (n < 0)
		n *= -1;
	return n;
}

int main(void)
{
	long x, y, l;
	long count = 0;

	scanf("%ld", &x);
	scanf("%ld", &y);
	scanf("%ld", &l);

	if (y >= 0) {
		if (x)
			count++;
	} else 
		count += 2;

	 x = absolute(x);
	 y = absolute(y);

	 count += x / l;
	 if (x % l)
		 count++;

	 count += y / l;
	 if (y % l)
		 count++;

	 printf("%ld\n", count);

	return 0;
}