#include <bits/stdc++.h>
using namespace std;
int main() {
  double pi = 3.141592653589793238462, n, r;
  cin >> n >> r;
  double c = (180.0 / n) * pi / 180;
  double m = r * sin(c) / (1 - sin(c));
  cout << fixed << setprecision(15) << m << endl;
  return 0;
}
