#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, r;
  cin >> n >> r;
  double pi = 3.14159265;
  double x = sin(pi / n);
  double t = x * r / (1 - x);
  cout << fixed << setprecision(7) << t << endl;
  return 0;
}
