#include<iostream>
using namespace std;
int main(){
	long long n,m,a,b,c;
	cin>>n>>m>>a;
	if(n%a==0){//afsdds
		b=n/a;
	}else{
		b=n/a+1;
	}
	if(m%a==0){
		c=m/a;
	}else{
		c=m/a+1;
	}
	cout<<b*c;
}