#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, r, ans, pi = acos(-1.0), Theta;
  scanf("%lf%lf", &n, &r);
  Theta = sin(pi / n);
  ans = Theta * r / (1.0 - Theta);
  printf("%.8f", ans);
}
