#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
int main() {
  int n, r;
  cin >> n >> r;
  double deg = (1.0 / n) * pi;
  double bi = sin(deg);
  cout << setiosflags(ios::fixed) << setprecision(10) << (bi / (1 - bi) * r)
       << endl;
  return 0;
}
