#include <iostream>
using namespace std;
int a, b, d, nr;
int main()
{
cin >> a >> b >> d;
if(a % d == 0 && b % d == 0) nr = (a / d) * (b / d);
else
if(a % d == 0 && b % d != 0) nr = (a / d) * ((b / d) + 1);
else
if(a % d != 0 && b % d == 0) nr = ((a / d) + 1) *(b / d);
else
if(a % d != 0 && b % d != 0) nr = ((a / d) + 1) * ((b / d) + 1);
cout << nr;
return 0;
}