#include <cstdio>

 #include <cstring>

 #include <cstdlib>

 #include <algorithm>

 #include <cmath>

 using namespace std;

 const double eps = 1e-;

 int N;

 double A;

 int dcmp( double a )

 {

     if ( fabs(a) < eps ) return ;

     return a <  ? - : ;

 }

 bool cal( double mid, double &ans )

 {

     double Hi2 = A, Hi1 = mid, Hi0;

     for ( int i = ; i < N - ; ++i )

     {

         Hi0 = 2.0 * ( Hi1 + 1.0 ) - Hi2;

         if ( dcmp( Hi0 ) <  ) return false;

         Hi2 = Hi1, Hi1 = Hi0;

     }

     ans = Hi0;

     return true;

 }

 int main()

 {

     while ( ~scanf( "%d%lf", &N, &A ) )

     {

         double l = 0.0, r = A;

         //int cnt = 0;

         double ans;

         while ( dcmp( r - l ) >  )

         {

             //++cnt;

             double mid = ( l + r ) / 2.0;

             //printf( "%f %f %f\n", l, r, mid );

             double tmp;

             if ( !cal( mid, tmp ) ) l = mid;

             else

             {

                 r = mid;

                 ans = tmp;

             }

             //if ( cnt > 100 ) break;

         }

         printf( "%.2f\n", ans );

     }

     return ;

 }