#include <bits/stdc++.h>
using ll = long long;
using namespace std;
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  int n, r;
  cin >> n >> r;
  double R = -r / (sin(acos(-1) / n) - 1);
  double ans = R - r;
  cout << fixed << setprecision(10) << ans;
}
