#include <bits/stdc++.h>
using namespace std;
double pi = acos(double(-1));
int main() {
  int n, r, R;
  cin >> n >> r;
  double q = 360.0 / (double)n;
  double t = q * pi / 180.0;
  t = t / 2.0;
  printf("%.7lf", r * sin(t) / (1.0 - sin(t)));
  return 0;
}
