Problem:
Score : 100 points

Problem Statement

Taro's summer vacation starts tomorrow, and he has decided to make plans for it now.

The vacation consists of N days.
For each i (1 \leq i \leq N), Taro will choose one of the following activities and do it on the i-th day:

A: Swim in the sea. Gain a_i points of happiness.

B: Catch bugs in the mountains. Gain b_i points of happiness.

C: Do homework at home. Gain c_i points of happiness.

As Taro gets bored easily, he cannot do the same activities for two or more consecutive days.

Find the maximum possible total points of happiness that Taro gains.

Constraints

All values in input are integers.

1 \leq N \leq 10^5

1 \leq a_i, b_i, c_i \leq 10^4

Input

Input is given from Standard Input in the following format:

N
a_1 b_1 c_1
a_2 b_2 c_2
:
a_N b_N c_N

Output

Print the maximum possible total points of happiness that Taro gains.

Sample Input 1

3
10 40 70
20 50 80
30 60 90

Sample Output 1

210

If Taro does activities in the order C, B, C, he will gain 70 + 50 + 90 = 210 points of happiness.

Sample Input 2

1
100 10 1

Sample Output 2

100

Sample Input 3

7
6 7 8
8 8 3
2 5 2
7 8 6
4 6 8
2 3 4
7 5 1

Sample Output 3

46

Taro should do activities in the order C, A, B, A, C, B, A.

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

// ReSharper disable ArrangeTypeMemberModifiers
// ReSharper disable ConvertIfStatementToSwitchStatement
// ReSharper disable FunctionRecursiveOnAllPaths
// ReSharper disable InconsistentNaming
// ReSharper disable InlineOutVariableDeclaration
// ReSharper disable InvertIf
// ReSharper disable JoinDeclarationAndInitializer
// ReSharper disable MemberCanBeMadeStatic.Global
// ReSharper disable MemberCanBeMadeStatic.Local
// ReSharper disable NonReadonlyMemberInGetHashCode
// ReSharper disable PossibleNullReferenceException
// ReSharper disable RedundantUsingDirective
// ReSharper disable SuggestVarOrType_BuiltInTypes
// ReSharper disable SuggestVarOrType_Elsewhere
// ReSharper disable TailRecursiveCall
// ReSharper disable UnusedMember.Global
// ReSharper disable UnusedMember.Local
// ReSharper disable UseObjectOrCollectionInitializert

#if true && UTAKA_LOCAL
//#if false
#define UTAKA_DEBUG
#endif

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Text;

namespace UtakaApp
{
    public partial class Program
    {
        //=========================================================================================
        // Answer
        //=========================================================================================

        public const string SiteName = "AtCoder";
        public const string ContestName = "dp";
        public const string ProblemName = "C";

        private readonly ConsoleInput cin;
        private readonly IConsole cou;

        public Program(ConsoleInput cin, IConsole cou)
        {
            this.cin = cin;
            this.cou = cou;
        }

        public static void Main(string[] args)
        {
#if UTAKA_LOCAL
//#if false
            new TestCaseCheckerForAtCoder().TestProblems();
#else
            var cin = new ConsoleInput(System.Console.In);
            var console = new MyConsole();
            new Program(cin, console).Solve();
            console.Flush();
#endif
        }

        private const int LargeValue = 1 << 30;

        public void Solve()
        {
            int N = cin.ReadInt;

            int[] A = new int[N];
            int[] B = new int[N];
            int[] C = new int[N];

            for (int i = 0; i < N; i++)
            {
                A[i] = cin.ReadInt;
                B[i] = cin.ReadInt;
                C[i] = cin.ReadInt;
            }

            // iは1はじまり
            // dp[i][j] : i日目に、行動jをとった場合の幸福度の最大値
            long[][] dp = JagArray2D<long>(N + 1, 3);

            for (int i = 1; i <= N; i++)
            {
                dp[i][0] = Math.Max(dp[i - 1][1] + A[i - 1], dp[i - 1][2] + A[i - 1]);
                dp[i][1] = Math.Max(dp[i - 1][2] + B[i - 1], dp[i - 1][0] + B[i - 1]);
                dp[i][2] = Math.Max(dp[i - 1][0] + C[i - 1], dp[i - 1][1] + C[i - 1]);
            }

            long ans = dp[N].Max();
            
            cou.WriteLine(ans);
            


//            int N = cin.ReadInt;
//
//            int K = cin.ReadInt;
//
//            int[] H = cin.ReadIntArray(N);
//
//            // dp[i] : 足場i にいるときの最小コスト
//            // 0はじまり
//
//            int[] dp = new int[N];
//            for (int i = 0; i < N; i++)
//            {
//                dp[i] = LargeValue;
//            }
//
//            dp[0] = 0;
//
//            for (int i = 0; i < N; i++)
//            {
//                for (int j = 1; j <= K; j++)
//                {
//                    if (i - j < 0) continue;
//
//                    dp[i] = Math.Min(dp[i], dp[i - j] + Math.Abs(H[i] - H[i - j]));
//                }
//            }
//
//            cou.WriteLine(dp[N - 1]);


//            // dp[i][j] : Mi ~ Mj までの計算の最小の掛け算の回数
//            //
//            // dp[i][j] = 0; if i == j
//            // dp[i][j] = min(i <= k < j)(dp[i][k] + dp[k + 1][j] + P[i - 1] * P[k] * P[j]; if i < j
//            int[][] dp = JagArray2D<int>(N + 1, N + 1, LargeValue);
//
//            for (int i = 0; i <= N; i++)
//            {
//                dp[i][i] = 0;
//            }
//
//            int[] P = new int[N + 1];
//
//            for (int i = 0; i < N; i++)
//            {
//                P[i] = cin.ReadInt;
//                P[i + 1] = cin.ReadInt;
//            }
//
//            for (int w = 2; w <= N; w++)
//            {
//                for (int i = 1; i <= N - w + 1; i++)
//                {
//                    int j = i + w - 1;
//
//                    //dp[i][j] = LargeValue;
//
//                    for (int k = i; k <= j - 1; k++)
//                    {
//                        dp[i][j] = Math.Min(dp[i][j], dp[i][k] + dp[k + 1][j] + P[i - 1] * P[k] * P[j]);
//                    }
//                }
//            }
//
//            cou.WriteLine(dp[1][N]);
        }
    }


    //=========================================================================================
    // Library
    //=========================================================================================

    public partial class Program
    {
        /// <summary>
        /// 要素数 (a, b) の、defaultValue で満たされた配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <param name="defaultValue">デフォルト値</param>
        /// <returns>指定した条件で初期化された配列</returns>
        public static T[,] Array2D<T>(int a, int b, T defaultValue)
            where T : struct
        {
            var ret = new T[a, b];
            for (int i = 0; i < a; i++)
            {
                for (int j = 0; j < b; j++)
                {
                    ret[i, j] = defaultValue;
                }
            }

            return ret;
        }

        /// <summary>
        /// 要素数 (a, b) のdefalut値で満たされた配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <returns>初期化された配列</returns>
        public static T[,] Array2D<T>(int a, int b)
            where T : struct
        {
            var ret = new T[a, b];
            return ret;
        }

        /// <summary>
        /// 要素数 (a, b) の、defaultValue で満たされたJag配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <param name="defaultValue">デフォルト値</param>
        /// <returns>指定した条件で初期化された配列</returns>
        public static T[][] JagArray2D<T>(int a, int b, T defaultValue)
            where T : struct
        {
            var ret = new T[a][];
            for (int i = 0; i < a; i++)
            {
                ret[i] = Enumerable.Repeat(defaultValue, b).ToArray();
            }

            return ret;
        }

        /// <summary>
        /// 要素数 (a, b) のdefalut値で満たされたJag配列を作成します。
        /// </summary>
        /// <typeparam name="T">配列の型</typeparam>
        /// <param name="a">1次元の要素数</param>
        /// <param name="b">2次元の要素数</param>
        /// <returns>初期化された配列</returns>
        public static T[][] JagArray2D<T>(int a, int b)
            where T : struct
        {
            var ret = new T[a][];
            for (int i = 0; i < a; i++)
            {
                ret[i] = new T[b];
            }

            return ret;
        }
    }

    //=========================================================================================
    // Debug IO
    //=========================================================================================

    public class ConsoleInput
    {
        private readonly char _separator = ' ';
        private readonly TextReader _stream;
        private readonly Queue<string> inputStream;

        public ConsoleInput(TextReader stream, char separator = ' ')
        {
            _separator = separator;
            _stream = stream;
            inputStream = new Queue<string>();
        }

        public string Read
        {
            get
            {
                if (inputStream.Count != 0)
                {
                    return inputStream.Dequeue();
                }

                var tmp = _stream.ReadLine().Split(_separator);
                for (var i = 0; i < tmp.Length; ++i)
                {
                    inputStream.Enqueue(tmp[i]);
                }

                return inputStream.Dequeue();
            }
        }

        public string ReadLine => _stream.ReadLine();
        public int ReadInt => int.Parse(Read);
        public long ReadLong => long.Parse(Read);
        public double ReadDouble => double.Parse(Read);

        public string[] ReadStrArray(long N)
        {
            var ret = new string[N];
            for (long i = 0; i < N; ++i)
            {
                ret[i] = Read;
            }

            return ret;
        }

        public int[] ReadIntArray(long N)
        {
            var ret = new int[N];
            for (long i = 0; i < N; ++i)
            {
                ret[i] = ReadInt;
            }

            return ret;
        }

        public long[] ReadLongArray(long N)
        {
            var ret = new long[N];
            for (long i = 0; i < N; ++i)
            {
                ret[i] = ReadLong;
            }

            return ret;
        }
    }

    public interface IConsole
    {
        void Flush();
        void Write(object obj);
        void Write(string str);
        void WriteLine(object obj);
        void WriteLine(string str);
    }

    public class MyConsole : IConsole
    {
        public MyConsole()
        {
            var sw = new StreamWriter(Console.OpenStandardOutput()) {AutoFlush = false};
            Console.SetOut(sw);
        }

        public void Flush()
        {
            Console.Out.Flush();
        }

        public void Write(object obj)
        {
            Write(obj.ToString());
        }

        public void Write(string str)
        {
            Console.Write(str);
        }

        public void WriteLine(object obj)
        {
            WriteLine(obj.ToString());
        }

        public void WriteLine(string str)
        {
            Console.WriteLine(str);
        }
    }

#if UTAKA_LOCAL

    public class DebugConsole : IConsole
    {
        private readonly StringBuilder mSb;

        public DebugConsole()
        {
            mSb = new StringBuilder();
        }

        public void Flush()
        {
            // 何もしない
        }

        public void Write(object obj)
        {
            Write(obj.ToString());
        }

        public void Write(string str)
        {
            mSb.Append(str);
        }

        public void WriteLine(object obj)
        {
            WriteLine(obj.ToString());
        }

        public void WriteLine(string str)
        {
            mSb.AppendLine(str);
        }

        public string GetAllOutput()
        {
            return mSb.ToString();
        }
    }

#endif

#if UTAKA_LOCAL

    public class TestCaseCheckerForAtCoder
    {
        private string GetDirectoryPath()
        {
            var problemPart = string.IsNullOrEmpty(Program.ProblemName)
                ? ""
                : $"/{Program.ProblemName}";

            return
                $"{Environment.GetFolderPath(Environment.SpecialFolder.UserProfile)}/AlgorithmPrac/{Program.SiteName}/{Program.ContestName}{problemPart}";
        }

        private string GetInputFilePath(int testCaseNumber)
        {
            return $"{GetDirectoryPath()}/sample-{testCaseNumber}.in";
        }

        private string GetOutputFilePath(int testCaseNumber)
        {
            return $"{GetDirectoryPath()}/sample-{testCaseNumber}.out";
        }

        public bool TestProblem(int testCaseNumber)
        {
            var inputFilePath = GetInputFilePath(testCaseNumber);
            var outputFilePath = GetOutputFilePath(testCaseNumber);

            TextReader inputStream = new StreamReader(inputFilePath);
            var cin = new ConsoleInput(inputStream);

            var debugConsoleWriter = new DebugConsole();

            new Program(cin, debugConsoleWriter).Solve();

            var output = debugConsoleWriter.GetAllOutput();

            TextReader outputStream = new StreamReader(outputFilePath);
            var outputAnswer = outputStream.ReadToEnd();

            Dbg.WriteLine(output);
            Dbg.WriteLine(outputAnswer);

            var isCorrect = output == outputAnswer;

            return isCorrect;
        }

        public void TestProblems(int targetTestCaseNumber = -1)
        {
            bool isSuccessAll = true;

            int testCaseNumber = 0;
            while (true)
            {
                testCaseNumber++;

                if (targetTestCaseNumber >= 0 && targetTestCaseNumber != testCaseNumber)
                {
                    continue;
                }

                var inputFileName = GetInputFilePath(testCaseNumber);
                if (!File.Exists(inputFileName))
                {
                    break;
                }

                Console.WriteLine($"TestCase {testCaseNumber} =====================================================");

                var result = TestProblem(testCaseNumber);

                if (result)
                {
                    Console.WriteLine("Success");
                }
                else
                {
                    isSuccessAll = false;
                    Console.WriteLine("Failure *****");
                }
            }

            if (isSuccessAll)
            {
                Console.WriteLine("!!!!!!!!! All Success !!!!!!!!!");
            }
        }
    }

#endif

#if UTAKA_LOCAL

    public static class Dbg
    {
        public static void WriteLine(string str)
        {
            Console.WriteLine(str);
        }

        public static void Write(string str)
        {
            Console.Write(str);
        }
    }
#else
    public static class Dbg
    {
        public static void WriteLine(string str)
        {
        }

        public static void Write(string str)
        {
        }
    }

#endif
}