#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  double n, r;
  cin >> n >> r;
  double alpha = acos(-1) / n;
  cout.precision(10);
  cout << r / (1 - sin(alpha)) - r;
  return 0;
}
