#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n, r;
  cin >> n >> r;
  double t = sin((2 * acos(0.0) / n));
  printf("%0.7f", (r * t) / (1 - t));
}
