#include <bits/stdc++.h>
using namespace std;
const int mx = 1234567;
const int md = 1e9 + 7;
int ar[mx], xar[mx], uses[mx], tab[105][105];
string st[1000];
long long arr[mx];
pair<int, string> pr[mx];
long long countSquares(long long a, long long b) {
  return (floor(sqrt(b)) - ceil(sqrt(a)) + 1);
}
set<int> s;
int main() {
  int tk, n, m, cs = 0;
  long long x, y, z;
  double R, nn;
  scanf("%lf%lf", &nn, &R);
  double c = (acos(0.0) * 2 / nn);
  double d = sin(c);
  double r = (R * d) / (1 - d);
  printf("%.10lf\n", r);
  return 0;
}
