#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;
ifstream f ("minesweeper.in");
ofstream g ("minesweeper.out");
double x;
int n, m;
long long int st, si, st1;
int main ()
{f>>n>>m;
x=28.928571/3;
cout<<x*n*m;
}