#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, r;
  cin >> n >> r;
  double k = 3.141592653589793238462643383279 / n;
  double m;
  m = r * sin(k) / (1 - sin(k));
  cout << fixed << setprecision(7) << m;
}
