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

int main(void) {
	int X, Y, L;
	int t;
	scanf("%d", &X);
	scanf("%d", &Y);
	scanf("%d", &L);
	
	t = 0;
	if(X != 0)t++;
	if(Y < 0)t += 2;
	X = abs(X);
	Y = abs(Y);
	
	t += X / L + ((X % L != 0)? 1 : 0);
	t += Y / L + ((Y % L != 0)? 1 : 0);

	printf("%d\n", t);
	
	return 0;
}