#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, r;
  cin >> n >> r;
  double lft = 0, rht = 1e8, mid;
  while (rht - lft >= 1e-9) {
    mid = (rht + lft) / 2;
    double val = n * asin(mid / (r + mid));
    if (val > M_PI)
      rht = mid;
    else
      lft = mid;
  }
  cout << fixed << setprecision(10) << rht;
}
