#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, a, t;
  while (cin >> n >> m >> a) {
    if (m < n) {
      t = m;
      m = n;
      n = t;
    }
    if (a >= m) cout << 1 << endl;
    if ((a < m) && (a >= n)) {
      if (m % a == 0)
        cout << m / a << endl;
      else
        cout << m / a + 1 << endl;
    }
    if ((a < n) && (m % a != 0) && (n % a != 0))
      cout << (m / a + 1) * (n / a + 1) << endl;
    if ((a < n) && (m % a != 0) && (n % a == 0))
      cout << (m / a + 1) * (n / a) << endl;
    if ((a < n) && (m % a == 0) && (n % a != 0))
      cout << (m / a) * (n / a + 1) << endl;
    if ((a < n) && (m % a == 0) && (n % a == 0))
      cout << (m / a) * (n / a) << endl;
  }
}
