#include <bits/stdc++.h>
using namespace std;
int main() {
  long double n, R;
  cin >> n >> R;
  long double den = 1 - sin(3.14159265358979323846 / n);
  long double num = R * sin(3.14159265358979323846 / n);
  long double ans = num / den;
  cout << fixed << setprecision(10) << ans;
}
