第二次周赛A

AC的代码如下：

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