#include<iostream>
int main(){
int n, m, a;
std::cin >> n >> m >> a;
int b = n / a;
if(n%a!=0) b++;
int c = m/a;
if(m%a!=0) c++;
std::cout << b*c;
return 0;
}
#include<iostream>
int main(){
int n, m, a;
std::cin >> n >> m >> a;
int b = n / a;
if(n%a!=0) b++;
int c = m/a;
if(m%a!=0) c++;
std::cout << b*c;
return 0;
}