defmodule Main do
  def main do
    IO.read(:line)

    IO.read(:line)
    |> String.trim()
    |> String.split()
    |> solve
    |> IO.puts()
  end

  def solve(a) do
    a
    |> Enum.uniq()
    |> Enum.map(fn x ->
      a
      |> Enum.chunk_by(fn y -> y == x end)
      |> Enum.filter(fn y -> y |> hd != x end)
      |> Enum.map(&length/1)
      |> Enum.max(&>=/2, fn -> 0 end)
      |> (&(&1 + 1)).()
    end)
    |> Enum.max()
  end
end