#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r;
  cin >> n >> r;
  double v1 = sin(3.1415926535897932384 / (double)n);
  double v2 = 1 - v1;
  cout << fixed << setprecision(10) << (r * v1) / (double)v2 << endl;
  return 0;
}
