use std::collections::HashMap;
const MAX_RC: usize = 3010;
#[derive(Default)]
//NOTE
//declare variables to reduce the number of parameters for dp and dfs etc.
struct Solver {}

impl Solver {
    fn solve(&mut self) {
        let stdin = std::io::stdin();
        let mut scn = Scanner {
            stdin: stdin.lock(),
        };
        let r: usize = scn.read();
        let c: usize = scn.read();
        let k: usize = scn.read();
        let mut cells = HashMap::new();
        (0..k).for_each(|_| {
            let r: usize = scn.read::<usize>() - 1;
            let c: usize = scn.read::<usize>() - 1;
            let v: usize = scn.read();
            cells.insert((r, c), v);
        });
        let mut dp = vec![vec![vec![0usize; 4]; MAX_RC]; MAX_RC];
        if let Some(v) = cells.get(&(0, 0)) {
            dp[0][0][1] = *v;
        }
        for y in 0..r {
            for x in 0..c {
                for k in 0..=3 {
                    //(i + 1, j)
                    let ny = y + 1;
                    let nx = x;
                    if let Some(v) = cells.get(&(ny, nx)) {
                        //pick
                        dp[ny][nx][1] = std::cmp::max(dp[ny][nx][1], dp[y][x][k] + v);
                    }
                    //not pick
                    dp[ny][nx][0] = std::cmp::max(dp[ny][nx][0], dp[y][x][k]);

                    //(i, j + 1)
                    let ny = y;
                    let nx = x + 1;
                    if let Some(v) = cells.get(&(ny, nx)) {
                        //pick
                        if k <= 2 {
                            dp[ny][nx][k + 1] = std::cmp::max(dp[ny][nx][k + 1], dp[y][x][k] + v);
                        }
                    }
                    //not pick
                    dp[ny][nx][k] = std::cmp::max(dp[ny][nx][k], dp[y][x][k]);
                }
            }
        }
        let result = dp[r - 1][c - 1].iter().max().unwrap();
        //eprintln!("{:?}", dp[r-1][c]);
        //eprintln!("{:?}", dp[r][c-1]);
        println!("{}", result);
    }
}

fn main() {
    std::thread::Builder::new()
        .stack_size(64 * 1024 * 1024) // 64MB
        .spawn(|| {
            let mut solver = Solver::default();
            solver.solve()
        })
        .unwrap()
        .join()
        .unwrap();
}
pub mod utils {
    const DYX: [(isize, isize); 8] = [
        (0, 1),   //right
        (1, 0),   //down
        (0, -1),  //left
        (-1, 0),  //top
        (1, 1),   //down right
        (-1, 1),  //top right
        (1, -1),  //down left
        (-1, -1), //top left
    ];

    pub fn try_adj(y: usize, x: usize, dir: usize, h: usize, w: usize) -> Option<(usize, usize)> {
        let ny = y as isize + DYX[dir].0;
        let nx = x as isize + DYX[dir].1;
        if ny >= 0 && nx >= 0 {
            let ny = ny as usize;
            let nx = nx as usize;
            if ny < h && nx < w {
                Some((ny, nx))
            } else {
                None
            }
        } else {
            None
        }
    }
}

//snippet from kenkoooo
pub struct Scanner<R> {
    stdin: R,
}

impl<R: std::io::Read> Scanner<R> {
    pub fn read<T: std::str::FromStr>(&mut self) -> T {
        use std::io::Read;
        let buf = self
            .stdin
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| b == b' ' || b == b'\n' || b == b'\r')
            .take_while(|&b| b != b' ' && b != b'\n' && b != b'\r')
            .collect::<Vec<_>>();
        unsafe { std::str::from_utf8_unchecked(&buf) }
            .parse()
            .ok()
            .expect("Parse error.")
    }
    pub fn read_line(&mut self) -> String {
        use std::io::Read;
        let buf = self
            .stdin
            .by_ref()
            .bytes()
            .map(|b| b.unwrap())
            .skip_while(|&b| b == b'\n' || b == b'\r')
            .take_while(|&b| b != b'\n' && b != b'\r')
            .collect::<Vec<_>>();
        unsafe { std::str::from_utf8_unchecked(&buf) }
            .parse()
            .ok()
            .expect("Parse error.")
    }
    pub fn vec<T: std::str::FromStr>(&mut self, n: usize) -> Vec<T> {
        (0..n).map(|_| self.read()).collect()
    }

    pub fn chars(&mut self) -> Vec<char> {
        self.read::<String>().chars().collect()
    }
}


Measured memory_bytes: 645236