#include <bits/stdc++.h>
using namespace std;
const long long int N = 1e6 + 9;
const long long int mod = 998244353;
map<long long int, long long int> mpp;
vector<long long int> v[N];
long long int a[N], parent[N], val[N];
set<long long int> st;
void solve() {
  long long int n, r;
  cin >> n >> r;
  cout << fixed << setprecision(8);
  double x = 3.14159265 / n;
  double angle = sin(x);
  double R = (r * angle) / (1 - angle);
  cout << R;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int t = 1;
  while (t--) solve();
}
