#include <bits/stdc++.h>
using namespace std;
const double PI = 3.141592653589793238463;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, r;
  cin >> n >> r;
  long double a = PI / n;
  long double ans = r * 1.0 * sin(a) / (1 - sin(a));
  cout << fixed << setprecision(10) << ans;
}
