#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1);
int main(void) {
  double n, r;
  while (scanf("%lf%lf", &n, &r) == 2) {
    printf("%.6f\n", sin(pi / (n)) * r / (1.0 - sin(pi / (n))));
  }
  return 0;
}
