#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r;
  cin >> n >> r;
  double ans = 1.0 * r * sin(3.1415926535897932384626433832795 / n) /
               (1.0 * (1 - sin(3.1415926535897932384626433832795 / n)));
  cout << fixed << setprecision(7) << ans;
}
