#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
long long n, r;
double pi = 3.141592653589793;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> r;
  double vall = (180.0000) / (0.0000 + n) * pi;
  vall /= 180.0000;
  double ans = r * sin(vall);
  ans = ans / (1 - sin(vall));
  cout << fixed << setprecision(12) << ans << '\n';
  return 0;
}
