#include <bits/stdc++.h>
using std::deque;
using std::make_pair;
using std::map;
using std::max;
using std::min;
using std::pair;
using std::set;
using std::string;
using std::vector;
constexpr long long magic_mod = 998244353;
long long m_pluss(long long a, long long b) { return (a + b) % magic_mod; }
long long m_mul(long long a, long long b) { return (a * b) % magic_mod; }
int main() {
  double pi = 3.14159265358979323846264338;
  double n, r;
  scanf("%lf%lf", &n, &r);
  double a = pi / n;
  double r1 = r * std::sin(a) / (1.0 - std::sin(a));
  printf("%.10lf\n", r1);
}
