#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;

const double pi = acos(-1);

int main()
{
    double h, r;
    cin >> h >> r;
    cout << fixed << setprecision(15) << -8.245 + 6.807 * h + 7.073 * 2 * r * pi << endl;
}