#include <bits/stdc++.h>
using namespace std;
bool myAssert(bool b);
void testDrivenDevelopment();
int start(int argc = 0, char const *argv[] = NULL);
vector<int> *g;
bool *isvisited;
int main(int argc, char const *argv[]) {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  double n, r, R, theta, secA;
  cin >> n >> r;
  theta = 1.0 * 2 * acos(0) / n;
  R = (r * sin(theta)) / (1 - sin(theta));
  cout << setprecision(8);
  cout << R << endl;
  return 0;
}
