program distinct_or_not
  implicit none
  integer :: n, a(200000) = 0, i
  read(*,*) n
  read(*,*) a(1:n)
  call quick_sort(a(1:n))
  do i = 2, n
    if (a(i) /= a(i-1)) cycle
    write(*,'(a)') "NO"
    stop
  end do
  write(*,'(a)') "YES"
contains
  subroutine swap(a,b)
    integer, intent(inout) :: a, b
    a = xor(a,b)
    b = xor(a,b)
    a = xor(a,b)
  end
  recursive subroutine quick_sort(a)
    integer, intent(inout) :: a(:)
    integer :: n, l, r, m
    integer :: p
    n = size(a)
    l = 1
    r = n
    m = (n+1)/2
    p = a(l)+a(m)+a(r)-max(a(l),a(m),a(r))-min(a(l),a(m),a(r))
    do
      do while (a(l) < p)
        l = l+1
      end do
      do while (a(r) > p)
        r = r-1
      end do
      if (l >= r) exit
      call swap(a(l),a(r))
      l = l+1
      r = r-1
    end do
    if (l-1 > 1) call quick_sort(a(1:l-1))
    if (n > r+1) call quick_sort(a(r+1:n))
  end
end program distinct_or_not