#![allow(non_snake_case)]
#![allow(dead_code)]
#![allow(unused_macros)]
#![allow(unused_imports)]

use std::str::FromStr;
use std::io::*;
use std::collections::*;
use std::cmp::*;

struct Scanner<I: Iterator<Item = char>> {
    iter: std::iter::Peekable<I>,
}

macro_rules! exit {
    () => {{
        exit!(0)
    }};
    ($code:expr) => {{
        if cfg!(local) {
            writeln!(std::io::stderr(), "===== Terminated =====")
                .expect("failed printing to stderr");
        }
        std::process::exit($code);
    }}
}

impl<I: Iterator<Item = char>> Scanner<I> {
    pub fn new(iter: I) -> Scanner<I> {
        Scanner {
            iter: iter.peekable(),
        }
    }

    pub fn safe_get_token(&mut self) -> Option<String> {
        let token = self.iter
            .by_ref()
            .skip_while(|c| c.is_whitespace())
            .take_while(|c| !c.is_whitespace())
            .collect::<String>();
        if token.is_empty() {
            None
        } else {
            Some(token)
        }
    }

    pub fn token(&mut self) -> String {
        self.safe_get_token().unwrap_or_else(|| exit!())
    }

    pub fn get<T: FromStr>(&mut self) -> T {
        self.token().parse::<T>().unwrap_or_else(|_| exit!())
    }

    pub fn vec<T: FromStr>(&mut self, len: usize) -> Vec<T> {
        (0..len).map(|_| self.get()).collect()
    }

    pub fn mat<T: FromStr>(&mut self, row: usize, col: usize) -> Vec<Vec<T>> {
        (0..row).map(|_| self.vec(col)).collect()
    }

    pub fn char(&mut self) -> char {
        self.iter.next().unwrap_or_else(|| exit!())
    }

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

    pub fn mat_chars(&mut self, row: usize) -> Vec<Vec<char>> {
        (0..row).map(|_| self.chars()).collect()
    }

    pub fn line(&mut self) -> String {
        if self.peek().is_some() {
            self.iter
                .by_ref()
                .take_while(|&c| !(c == '\n' || c == '\r'))
                .collect::<String>()
        } else {
            exit!();
        }
    }

    pub fn peek(&mut self) -> Option<&char> {
        self.iter.peek()
    }
}

fn main() {
    let cin = stdin();
    let cin = cin.lock();
    let mut sc = Scanner::new(cin.bytes().map(|c| c.unwrap() as char));
    let R: usize = sc.get();
    let C: usize = sc.get();
    let K: usize = sc.get();
    let mut v: Vec<Vec<usize>> = vec![vec![0; C]; R];
    for _ in 0..K {
        let r: usize = sc.get();
        let c: usize = sc.get();
        let vi: usize = sc.get();
        v[r-1][c-1] = vi;
    }
    let mut dp = vec![vec![vec![0; 3+1]; C]; R];
    dp[0][0][0] = 0;
    for r in 0..R {
        for c in 0..C {
            for k in 0..=3 {
                if r < R-1 {
                    if k < 3 {
                        dp[r+1][c][0] = max(dp[r+1][c][0], dp[r][c][k] + v[r][c]);
                    } else {
                        dp[r+1][c][0] = max(dp[r+1][c][0], dp[r][c][k]);
                    }
                }
                if c < C-1 {
                    if k < 3 {
                        dp[r][c+1][k+1] = max(dp[r][c+1][k], dp[r][c][k] + v[r][c]);
                    }
                    dp[r][c+1][k] = max(dp[r][c+1][k], dp[r][c][k]);
                }
            }
        }
    }
    for k in 0..3 {
        dp[R-1][C-1][k] += v[R-1][C-1];
    }
    let mut ans = 0;
    for k in 0..=3 {
        ans = max(ans, dp[R-1][C-1][k]);
    }
    println!("{}", ans);
}


Measured memory_bytes: 705328