#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define rep1(i, n) for (ll i = 1; i < (n); ++i)
#define rrep(i, n) for (ll i = n; i > 0; --i)
#define bitrep(i, n) for (ll i = 0; i < (1 << n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define yesNo(b) ((b) ? "Yes" : "No")
using ll = long long;
using ull = unsigned long long;
using ld = long double;
string alphabet = "abcdefghijklmnopqrstuvwxyz";
string ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const double pi = 3.141592653589793;
int smallMOD = 998244353;
int bigMOD = 1000000007;

int main()
{
    // インドゾウの表面積を求めてください
    // インドゾウの高さhと前足の半径rが与えられます
    ld h, r;
    cin >> h >> r;
    cout << fixed << setprecision(20) << -8.245 + 6.807 * h + 7.073 * r * 2 * pi << endl;
    return 0;
}