#include <bits/stdc++.h>
using namespace std;
double pi = acos(-1.0);
int main() {
  double n, r;
  scanf("%lf %lf", &n, &r);
  double sin_val, sin_val2, x, y, ri;
  sin_val = (pi / n);
  y = sin(sin_val);
  ri = (y * r) / (1.0 - y);
  printf("%.7lf", ri);
  return 0;
}
