!!!**********************************************************************
program main
!!!**********************************************************************  

  integer   :: n, d, x
  real      :: a
  ! character ::
  
!!!----------------------------------------------------------------------

  read ( unit = *, fmt = * ) n, d

  
  a = ceiling ( real ( 2 * d + 1 ) / real ( n ) )

  x = 0
  
  do

     if ( real ( x ) < a  ) then

        x = x + 1
        
     else

        x = x + 1

        exit
        
     end if
     

  end do
  
  
  print "(i0)", x  
  
!!!**********************************************************************  
end program main
!!!**********************************************************************
