#include <bits/stdc++.h>
using namespace std;
class Solution {
 public:
  long double calc(int n, int r) {
    long double deg = 3.14159265358979323846 / n;
    long double s = sin(deg);
    long double R = r * s / (1 - s);
    return R;
  }
};
int main(int argc, char** argv) {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(10);
  Solution sol;
  int n, r;
  cin >> n >> r;
  cout << sol.calc(n, r) << endl;
  return 0;
}
