#include <bits/stdc++.h>
int main() {
  double n, r, ans, t, pi;
  scanf("%lf %lf", &n, &r);
  pi = acos(-1);
  t = pi / n;
  ans = (r * sin(t)) / (1 - sin(t));
  printf("%.7f\n", ans);
  return 0;
}
