#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  int n, r;
  cin >> n >> r;
  double p = sin(3.1415926535 / n);
  double l = (r * p) / (1 - p);
  cout << fixed << setprecision(7) << l;
}
