using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using static System.Console;
using static System.Math;
using static Atcoder.IO;

namespace Atcoder
{
    class Program
    {
        static StreamWriter sw = new StreamWriter(OpenStandardOutput()) { AutoFlush = false };
        static void Main(string[] args)
        {
            try
            {
                SetOut(sw);
                Solve.Answer();
                Out.Flush();
            }
            catch (Exception ex)
            {
                WriteLine(ex.ToString());
                Out.Flush();
            }
        }
    }

    public class Solve
    {
        public static void Answer()
        {
            var RCK = RSInt;
            var R = RCK[0];
            var C = RCK[1];
            var K = RCK[2];

            var map = new int[R][];
            for (int i = 0; i < R; i++)
            {
                map[i] = new int[C];
            }
            for (int i = 0; i < K; i++)
            {
                var rcv = RSInt;
                rcv[0]--;
                rcv[1]--;
                map[rcv[0]][rcv[1]] = rcv[2];
            }

            var dp = new long[R + 1][][];
            for (int i = 0; i < R + 1; i++)
            {
                dp[i] = new long[C + 1][];
                for (int j = 0; j < C + 1; j++)
                {
                    dp[i][j] = new long[4];
                }
            }
            for (int i = 0; i < R + 1; i++)
            {
                for (int j = 0; j < C + 1; j++)
                {
                    for (int k = 0; k < 4; k++)
                    {
                        if (i < R && j < C && k < 3)
                        {
                            dp[i + 1][j][0] = Max(dp[i + 1][j][0], dp[i][j][k] + map[i][j]);
                            dp[i][j + 1][k + 1] = Max(dp[i][j + 1][k + 1], dp[i][j][k] + map[i][j]);
                        }
                        if (i < R)
                        {
                            dp[i + 1][j][k] = Max(dp[i + 1][j][k], dp[i][j][k]);
                        }
                        if (j < C)
                        {
                            dp[i][j + 1][k] = Max(dp[i][j + 1][k], dp[i][j][k]);
                        }
                    }
                }
            }
            WriteLine(dp.Last().Last().Max());
        }
    }

    public class IO
    {
        #region Input
        public static int RInt => int.Parse(ReadLine());
        public static long RLong => long.Parse(ReadLine());
        public static double RDouble => double.Parse(ReadLine());

        public static string[] RSString => ReadLine().Split();
        public static int[] RSInt => ReadLine().Split().Select(s => int.Parse(s)).ToArray();
        public static long[] RSLong => ReadLine().Split().Select(s => long.Parse(s)).ToArray();
        public static double[] RSDouble => ReadLine().Split().Select(s => double.Parse(s)).ToArray();
        #endregion

        #region Output
        public static void OutJoinSpace<T>(IEnumerable<T> list) => WriteLine(string.Join(" ", list));
        public static void WriteLineYes_or_No(bool flag) => WriteLine(flag ? "Yes" : "No");
        public static void WriteLineYES_or_NO(bool flag) => WriteLine(flag ? "YES" : "NO");
        #endregion
    }

    public class Mod
    {
        #region
        private readonly static long M = 1000000007;

        public static long Add(long a, long b) => (a * b) % M;
        public static long Sub(long a, long b) => (a - b) % M >= 0 ? (a - b) % M : (a - b) % M + M;
        public static long Multi(long a, long b) => (a * b) % M;
        #endregion
    }
}

Measured memory_bytes: 633148