import java.util.*;
import java.io.*;
import java.util.concurrent.*;
public class Main
{

    static long[][][] dp = new long[3001][3001][4];
    static long[][] grid = new long[3001][3001];
    static int r,c,k,a,b;
    static long cc;
    public static void main(String[] args) throws IOException
    {
        Reader in = new Reader();
        r = in.nextInt();
        c = in.nextInt();
        k = in.nextInt();

        for (int i=0;i<=3000;i++){
            for(int j=0;j<=3000;j++){
                for(int k=0;k<=3;k++){
                    dp[i][j][k] = -1;
                }
            }
        }
        for (int i=0;i<=3000;i++){
            for(int j=0;j<=3000;j++){
                grid[i][j] = 0;
            }
        }

        for(int i=0;i<k;i++){
            a = in.nextInt();
            b = in.nextInt();
            cc = in.nextLong();
            a--;
            b--;
            grid[a][b] = cc;
        }

        System.out.println(rec(0,0,0));
    }

    static long rec(int i,int j,int taken){

        if(i==r || j==c)
            return 0;
        if(dp[i][j][taken]!=-1)
            return dp[i][j][taken];
        long temp1 = 0;

        if(taken<3){
            temp1 = grid[i][j]+Math.max(rec(i+1,j,0),rec(i,j+1,taken+1));
        }
        long temp2 = Math.max(rec(i+1,j,0),rec(i,j+1,taken));
        dp[i][j][taken] = Math.max(temp1,temp2);
        return dp[i][j][taken];
    }

    static class Reader
    {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader()
        {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException
        {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException
        {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1)
            {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do
            {
                ret = ret * 10 + c - '0';
            }  while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException
        {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException
        {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');

            if (c == '.')
            {
                while ((c = read()) >= '0' && c <= '9')
                {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException
        {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException
        {
            if (din == null)
                return;
            din.close();
        }
    }

}

Measured memory_bytes: 593068