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