program main
Implicit None
	integer(8)::n,k,i,j,a
	real(8)::p=0,q
	
	read*,n,k
	
	do i = 1,n
		a = i
		j = 0
		do
		if(a >= k) exit
		a = a*2
		j = j+1
		enddo
		
		q = (5d-1)**real(j)
		p = p+q
	enddo
	p = p/n
	
	print *,p
end program main