#include <bits/stdc++.h>
using namespace std;
double cot(double a) { return 1 / tan(a); }
double a1(double n, double Rc, double rp) {
  int q = 0;
  return n * rp * sqrt((Rc * Rc) - (rp * rp));
}
double a2(double n, double rp) {
  int q = 0;
  return (n * rp * rp * cot(4 * atan(1) / n));
}
double dif(double d1, double d2) {
  if (d1 > d2) {
    return d1 - d2;
  }
  return d2 - d1;
}
int main() {
  double n, r, mid;
  scanf("%lf %lf", &n, &r);
  double rmax = 1000, rmin = 0;
  mid = (rmax + rmin) / 2;
  double A1 = a1(n, r + mid, mid);
  double A2 = a2(n, mid);
  double d = dif(A1, A2);
  while (d > 0.0000000001) {
    if (A2 < A1) {
      rmin = mid;
    } else {
      rmax = mid;
    }
    mid = (rmax + rmin) / 2;
    A1 = a1(n, r + mid, mid);
    A2 = a2(n, mid);
    d = dif(A1, A2);
  }
  printf("%lf\n", mid);
}
