#include <iostream>
using namespace std;
long long a,b,c;
int main() {
cin >> a >> b >> c;
if(a < c || b < c) {
cout << 0;
}
else {
long long s = (a/c) * (b/c);
long long in = max(0ll, (a/c-2)) * max((b/c-2), 0ll);
cout << s - in;
}
}