#include<iostream>
#include <fstream>
#include <algorithm>
#include <cmath>
using namespace std;

int main(){
	ifstream fin("DATA2.txt");
	ofstream fout("OUT2.txt");
	double x,y;
	fin >> x >> y;
	fout << (int) ceil((x*x*y/3.0)) << endl;
	fin.close(); fout.close();
	return 0;
}