#include<iostream>
using namespace std;
long long int n,m,a;
int main(){
	long long int x,y;
	cin>>n>>m>>a;
	if(n%a==0)x=n/a;
	if(m%a==0)y=m/a;
	if(n%a!=0)x=n/a+1;
	if(m%a!=0)y=m/a+1;
	cout<<x*y;
	return 0;
}