#include <bits/stdc++.h>
using namespace std;
const long double PI = 3.14159265;
int main() {
  cout << setprecision(16) << fixed;
  long double ans, n, r;
  cin >> n >> r;
  ans = r / (sqrt((2 / (1 - cos((2 * PI / n))))) - 1);
  cout << ans;
  return 0;
}
