#include <bits/stdc++.h>
using namespace std;
const int nn = 115;
const double PI = 2 * acos(0);
int main() {
  int n;
  double r;
  double ans;
  cin >> n >> r;
  double x = (PI * (180 - (360.0 / n)) / 2.0) / 180.0;
  double L = 0, R = 1e5;
  while (L <= R) {
    double mid = (L + R) / 2.0;
    if (fabs(cos(x) * (mid + r) - mid) < 1e-9) {
      ans = mid;
      break;
    } else if (cos(x) * (mid + r) > (mid)) {
      L = mid;
    } else {
      R = mid;
    }
  }
  printf("%.6f\n", ans);
}
