#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r;
  cin >> n >> r;
  double the = 3.14159265358979323846 / n;
  double ans = sin(the);
  ans = (r * ans) / (1 - ans);
  cout.setf(ios::fixed);
  cout << setprecision(6) << ans << endl;
}
