func_code_string: #include <bits/stdc++.h>   using namespace std;   const double pi = acos(-1);   int main() {     int n;     double R, r;     double st;     while (scanf( %d %lf , &n, &R) != EOF) {       st = pi / (1.0 * n);       r = sin(st) * R / (1 - sin(st));       printf( %.7lf n , r);     }     return 0;   }   