#include <bits/stdc++.h>
using namespace std;
long long pow_mod(long long x, long long y) {
  long long r = 1;
  for (; y; y >>= 1, x = (long long)x * x % 1000000007)
    if (y & 1) r = (long long)r * x % 1000000007;
  return r;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long double n, r;
  cin >> n >> r;
  cout << fixed << setprecision(10);
  cout << r * sin(3.14159265 / n) / (1 - sin(3.14159265 / n));
}
