#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r;
  double angle, ans;
  cin >> n >> r;
  angle = 3.14159265 / n;
  ans = (r * sin(angle)) / (1 - sin(angle));
  cout << fixed << setprecision(7) << ans << "\n";
  return 0;
}
