#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  double n, r;
  cin >> n >> r;
  double num = r * (sin(3.141592653589793 / n));
  double den = 1 - sin(3.141592653589793 / n);
  cout << setprecision(15);
  cout << num / den;
}
