#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  double n, r;
  cin >> n >> r;
  double sinTheta = sin(3.1415926535 / n);
  double ans = (r * sinTheta) / (1.0 - sinTheta);
  cout << fixed;
  cout << setprecision(10) << ans;
}
