1A - Theater Square

#include <iostream>
#include <cstdlib>
#include <cmath>

int main()
{
    int m, n, a;
    std::cin >> m >> n >> a;
    double double_a = static_cast<double>(a);
    std::cout << static_cast<long long>(std::ceil(m / double_a) * std::ceil(n / double_a)) << std::endl;
    return EXIT_SUCCESS;
}