#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r;
  cin >> n >> r;
  double R = r / ((1 / sin(3.14159265 / n) - 1));
  cout << fixed << showpoint;
  cout << setprecision(10);
  cout << R << endl;
  return 0;
}
