#include <bits/stdc++.h>
using namespace std;
template <typename t1, typename t2>
istream& operator>>(istream& in, pair<t1, t2>& p) {
  in >> p.first >> p.second;
  return in;
}
template <typename t1, typename t2>
ostream& operator<<(ostream& out, pair<t1, t2>& p) {
  out << p.first << " " << p.second;
  return out;
}
template <typename t>
ostream& operator<<(ostream& out, vector<t>& v) {
  for (auto& i : v) {
    out << i << "\n";
  }
  return out;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n, R;
  cin >> n >> R;
  long double alpha = 2.0 * M_PI / (long double)n;
  long double cosa = cosl(alpha);
  long double A = 1.0 + cosa;
  long double B = 2.0 * (long double)R * (cosa - 1.0);
  long double C = (long double)R * (long double)R * (cosa - 1.0);
  long double delta = sqrtl(B * B - 4.0 * A * C);
  long double r1 = (-B + delta) / (2.0 * A);
  long double r2 = (-B - delta) / (2.0 * A);
  long double r = max(r1, r2);
  cout << fixed << setprecision(12) << r;
  return 0;
}
