#include <bits/stdc++.h>
using namespace std;
using ld = long double;
ld n, r, s;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> r;
  s = sinl(acosl(-1.0L) / n);
  cout << fixed << setprecision(8) << (r * s / (1 - s)) << "\n";
}
