1A

#include <iostream>
using namespace std;

int main()
{
	long long n, m, a, r, c;
	cin>>n>>m>>a;
	r=n/a;
	if(n%a!=0)
		++r;
	c=m/a;
	if(m%a!=0)
		++c;
	cout<<r*c<<endl;
	return 0;
}