//Haha TTpro
//A. Theatre Square
//http://codeforces.com/problemset/problem/1/A

#include <iostream>
using namespace std;
int main()
{
	long long int m, n, a;
	cin >> n >> m >> a;
	long long int ngang, doc;
	ngang = m / a;
	if (m%a != 0)
	{
		ngang++;
	}

	doc = n / a;

	if (n%a != 0)
	{
		doc++;
	}
	
	long long int tong;
	tong = ngang*doc;
	cout << tong;
	return 0;

}