#include <bits/stdc++.h>   using namespace std;   const double EPS = 1e-6;   double n, r;   bool check(double R) {     double x1 = r + R;     double y1 = 0;     double x2 = cos(2 * acos(-1) / n) * (r + R);     double y2 = sin(2 * acos(-1) / n) * (r + R);     double len = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));     if (len <= 2 * R)       return true;     else       return false;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n >> r;     double l1 = 0, r1 = 10000;     for (int i = 0; i < 500; i++) {       double mm = (l1 + r1) / 2.0;       if (check(mm))         r1 = mm;       else         l1 = mm;     }     cout.fixed;     cout.precision(15);     cout << l1;     return 0;   }   