#include <bits/stdc++.h>
using namespace std;
int main() {
  int r, n;
  double pi = 3.14159265359;
  cin >> n >> r;
  double theta = 2 * pi / n, a, b;
  double sol = r / (1 / sin(theta / 2) - 1);
  printf("%0.10f", sol);
  return 0;
}
