Codeforces_1A

//Codeforces Round 1A
#include <cmath>
#include <iomanip>
#include <iostream>
using namespace std;
int main()
{
    long double n, m, a;
    cin >> n >> m >> a;
    cout << fixed << setprecision(0) << ceil(m/a)*ceil(n/a);
    return 0;
}