Imports System

Public Class Program

    Public Shared Sub Main(args As String())
        Dim N As Integer = Integer.Parse(Console.ReadLine)
        Dim Ai() As Integer = Array.ConvertAll(Of String, Integer)(Console.ReadLine.Split(" "), AddressOf Integer.Parse)
        Dim Aj() As Integer = Array.ConvertAll(Of String, Integer)(Console.ReadLine.Split(" "), AddressOf Integer.Parse)

        Dim maxsum As Integer = 0

        For i As Integer = 0 To N - 1

            Dim sum As Integer = 0

            For j As Integer = 0 To N - 1

                If j <= i Then
                    sum += Ai(j)
                End If

                If j >= i Then
                    sum += Aj(j)
                End If
            Next

            If sum > maxsum Then
                maxsum = sum
            End If

        Next


        Console.WriteLine(maxsum)
    End Sub
End Class