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

int main(){
    int x,y,l;
    scanf("%d %d %d",&x,&y,&l);
    int res = 0;

    if((0 < x && 0 < y) || (x < 0 && 0 <= y)){
        res++;
    }
    else if((x < 0 && y <= 0) || (x <= 0 && y < 0)){
        res+=2;
    }

    res += (int)ceil(fabs((double)x)/l);
    res += (int)ceil(fabs((double)y)/l);

    printf("%d\n",res);

    return 0;
}