#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, b;
  cin >> n >> b;
  double alfa = 3.1415926535 * (n - 2) / n;
  alfa /= 2;
  double ans = b * cos(alfa) / (1 - cos(alfa));
  cout << fixed << setprecision(12) << ans << endl;
}
