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

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