#include <bits/stdc++.h>
using namespace std;
int main() {
  double n, r;
  while (cin >> n >> r) {
    double d = 0;
    d = 360.0 / n / 2;
    double s;
    s = sin(d * 3.1415926 / 180);
    double R = r * s / (1 - s);
    printf("%.8lf\n", R);
  }
  return 0;
}
