program main

  implicit none

  integer    :: n, k
  integer,allocatable :: p(:)
  real   ,allocatable :: h(:)
  real   ,allocatable :: sh(:)
  integer :: i, j 
  
  read(*,*) n, k
  allocate( p(n) )
  allocate( h(n) )
  read(*,*) p

  h = 0e0 
  do i = 1, n
    do j = 1, p(i)
      h(i) = h(i) + j 
    end do
    h(i) = h(i) / p(i) 
  end do

  allocate( sh(n-k+1) )
  do i = 1, n-k+1
    sh(i) = sum( h(i:i+k-1) )
  end do
  
  print*, maxval( sh )
end program main

recursive subroutine quicksort1(a, first, last)
  !call quicksort1( a, 1, n ) 
  implicit none
  integer(8),intent(inout)::a(*)
  integer,intent(in)::first,last
  !
  ! Original
  ! https://gist.github.com/t-nissie/479f0f16966925fa29ea
  !
  integer(8)::x,t
  integer::i,j

  x = a((first+last)/2)
  i = first
  j = last
  do
     do while (a(i) < x)
        i=i+1
     end do
     do while (x < a(j))
        j=j-1
     end do
     if (i >= j) exit
     t = a(i)
     a(i) = a(j)
     a(j) = t
     i=i+1
     j=j-1
  end do
  if (first < i-1) call quicksort1(a, first, i-1)
  if (j+1 < last)  call quicksort1(a, j+1, last)

  return
end subroutine quicksort1
