#include <bits/stdc++.h>
using namespace std;
double pi = 3.1415926535;
int main() {
  double r1, n;
  while (~scanf("%lf%lf", &n, &r1)) {
    double r2 = (r1 * sin(pi / n)) / (1.0 - sin(pi / n));
    printf("%.7lf\n", r2);
  }
  return 0;
}
