#include <bits/stdc++.h>
using namespace std;
const int N = 1e3;
double n, r, res;
double pi = acos(-1);
int main() {
  cin >> n >> r;
  res = (sin(pi / n) * r) / (1.0 - sin(pi / n));
  cout << setprecision(6) << fixed << res << endl;
}
