#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
const int mo = 1e9 + 7;
long long n, r;
double R;
int main(void) {
  cin >> n >> r;
  double A = sin(3.141592653589793 / n);
  printf("%.7f\n", r * A / (1 - A));
  return 0;
}
