#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    int ew,ns,eworg,fwd,ordertimes=0;
    scanf("%d",&ew);
    scanf("%d",&ns);
    scanf("%d",&fwd);
    if(ew!=0)
    {
        eworg=ew;
        ordertimes++;
        if(ew<0)
        {
            ew=ew*-1;
        }
        while(ew>0)
        {
            ew-=fwd;
            ordertimes++;
        }
    }
    if(ns!=0)
    {
        if(eworg!=0)
        {
            ordertimes++;
        }
        else
        {
            ordertimes+=2;
        }
        if(ns<0)
        {
            ns=ns*-1;
        }
        while(ns>0)
        {
            ns-=fwd;
            ordertimes++;
        }
    }
    printf("%d\n",ordertimes);
}