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