#include <bits/stdc++.h>
using namespace std;
const long double PI = acos(-1.0L);
const long double EPS = 1e-12L;
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
namespace task {
long double n, r, a;
int main() {
  cin >> n >> r;
  a = sin(PI / n);
  cout << r * a / (1 - a) << '\n';
  return 0;
}
}  // namespace task
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(11);
  cout.setf(ios::fixed);
  return task::main();
}
