#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  double n, r, R, i, j, k;
  cin >> n >> r;
  double n1, n2;
  n1 = 360 / n;
  n1 = n1 / 2;
  n2 = n1 * (3.1415926535897932384626 / 180);
  double ang = sin(n2);
  double ans = (ang * r) / (1 - ang);
  cout << fixed << setprecision(7) << ans;
  return 0;
}
