#include <bits/stdc++.h>
#include<atcoder/all>
using namespace atcoder;
#define rep(i, n) for(ll i = 0; i < n; i++)
#define rep2(i, m, n) for(ll i = m; i <= n; i++)
#define rrep(i, m, n) for(ll i = m; i >= n; i--)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define MAX(x) *max_element(all(x))
#define MIN(x) *min_element(all(x))
#define SZ(a) ((ll)(a).size())
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
const ll mod = 1000000007;
const int dx[4] = { 1, 0, -1, 0 };
const int dy[4] = { 0, 1, 0, -1 };
const int inf = 1e9 + 1;
const ll INF = 1e18 + 1;
const double pi = acos(-1);

using Graph = vector<vector<int>>;
Graph G;

//typedef atcoder::modint1000000007 mint;
typedef atcoder::modint998244353 mint;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

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