#include <bits/stdc++.h>
using namespace std;
int main() {
  int q = 1;
  while (q--) {
    double n, r;
    cin >> n >> r;
    double ans;
    ans = (r) / (1 / sin(3.14159265 / n) - 1);
    cout << setprecision(9) << ans;
  }
}
