#include <bits/stdc++.h>
using namespace std;
const double EPS = 1e-6;
double n, r;
bool check(double R) {
  double x1 = r + R;
  double y1 = 0;
  double x2 = cos(2 * acos(-1) / n) * (r + R);
  double y2 = sin(2 * acos(-1) / n) * (r + R);
  double len = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
  if (len <= 2 * R)
    return true;
  else
    return false;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> r;
  double l1 = 0, r1 = 10000;
  for (int i = 0; i < 500; i++) {
    double mm = (l1 + r1) / 2.0;
    if (check(mm))
      r1 = mm;
    else
      l1 = mm;
  }
  cout.fixed;
  cout.precision(15);
  cout << l1;
  return 0;
}
