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

int main()
{
    double n,m,a;
    double ans;

    while(scanf("%lf %lf %lf",&n,&m,&a)==3){

        double tmp=ceil(n/a);
        double tmp1=ceil(m/a);

            //printf("%lf\n",tmp);
          //   printf("%lf\n",tmp1);

        ans= tmp*tmp1;

        printf("%.0lf\n",ans);

    }


    return 0;
}