#include <stdio.h>

int main(void) {
	// your code goes here
	int x, y, l, m;
	
	scanf("%d", &x);
	scanf("%d", &y);
	scanf("%d", &l);
	
	if(x==0 && y>0){
		m= (int)ceil((double)y/(double)l);
	}else if(x==0 && y<0){
		m= (int)ceil(fabs((double)y)/(double)l) + 2;
	}else if(y==0){
		m= (int)ceil(fabs((double)x)/(double)l) + 1;
	}else if(y>0){
		m= (int)ceil(fabs((double)x)/(double)l) + (int)ceil(fabs((double)y)/(double)l) + 1;
	}else if(y<0){
		m= (int)ceil(fabs((double)x)/(double)l) + (int)ceil(fabs((double)y)/(double)l) + 2;
	}
	if(x==0 && y==0){
		m= 0;
	}
	
	printf("%d\n", m);
	
	return 0;
}