#include <iostream>
using namespace std;
int main() {
long long a,b,c;
cin>>a>>b>>c;
long long widthwise = a / c;
if(a % c != 0){
widthwise++;
}
long long lengthwise = b / c;
if(b % c != 0){
lengthwise++;
}
long long result = lengthwise*widthwise;
cout<<result;
return 0;
}