#include <bits/stdc++.h>
using namespace std;
const int N = 200002;
using namespace std;
long double getTan(long double x) { return sin(x); }
int main() {
  long double n, r;
  cin >> n >> r;
  cout << fixed << setprecision(10)
       << r * getTan(3.1415926535897932 / n) /
              (1 - getTan(3.1415926535897932 / n));
  return 0;
}
