#include<stdio.h>
int main(){
int a,m,n,x,y;
scanf("%d %d %d",&m,&n,&a);
if (m%a==0)
	x=m/a;
else 
	x=(m/a)+1;//xzhi
if (n%a==0)
	y=n/a;
else 
	y=(n/a)+1;//yzhi
printf("%d\n",x*y);
return 0;
}