#include <bits/stdc++.h>
using namespace std;
int num1[100005];
int weada[100005];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, m;
  cin >> n >> m;
  double s = sin((double)acos(-1) / n);
  cout << setprecision(12) << (double)(m * s) / (1.0 - s) << endl;
}
