using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var a = NList;
        var b = NList;
        var c = NList;
        var dp = new long[5][];
        for (var i = 0; i < dp.Length; ++i) dp[i] = new long[n + 1];
        for (var i = 0; i < n; ++i)
        {
            var max = dp[0][i];
            dp[0][i + 1] = max + a[i];
            max = Math.Max(max, dp[1][i]);
            dp[1][i + 1] = max + b[i];
            max = Math.Max(max, dp[2][i]);
            dp[2][i + 1] = max + c[i];
            max = Math.Max(max, dp[3][i]);
            dp[3][i + 1] = max + b[i];
            max = Math.Max(max, dp[4][i]);
            dp[4][i + 1] = max + a[i];
        }
        var ans = dp.Max(di => di[n]);
        dp = new long[5][];
        for (var i = 0; i < dp.Length; ++i) dp[i] = new long[n + 1];
        for (var i = 0; i < n; ++i)
        {
            var max = dp[0][i];
            dp[0][i + 1] = max + a[i];
            max = Math.Max(max, dp[1][i]);
            dp[1][i + 1] = max + b[i];
            max = Math.Max(max, dp[2][i]);
            dp[2][i + 1] = max + a[i];
            max = Math.Max(max, dp[3][i]);
            dp[3][i + 1] = max + b[i];
            max = Math.Max(max, dp[4][i]);
            dp[4][i + 1] = max + a[i];
        }
        WriteLine(Math.Max(ans, dp.Max(di => di[n])));
    }
}