CodeForces 1A and tutorial in http://algocoding.wordpress.com/2013/03/09/codeforces-tutorial-1-introduction/
#include <iostream>
using namespace std;
int main() {
long long int n;
long long int m;
long long int a;
cin >> n;
cin >> m;
cin >> a;
long long int titles1 = n/a;
long long int titles2 = m/a;
if (n%a != 0) titles1++;
if (m%a != 0) titles2++;
long long int result = titles1*titles2;
cout << result;
return 0;
}