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

fn main() {
  let mut input = Input::new();

  let H = input.read::<usize>();
  let W = input.read::<usize>();
  let K = input.read::<usize>();
  let mut treasures = vec![vec![0; W]; H];
  for _ in 0 .. K {
    let x = input.read::<usize>() - 1;
    let y = input.read::<usize>() - 1;
    let v = input.read::<i64>();
    treasures[x][y] = v;
  }

  let mut ans = 0;
  for i0 in 0 .. H {
    for j0 in 0 .. W {
      for i in 0 .. H {
        for j in 0 .. W {
          if i + j >= i0 + j0 && i + j0 >= i0 + j {
            ans += treasures[i][j];
            ans %= 998244353;
          }
        }
      }
    }
  }

  println!("{}", ans);
}

type Int = i64;
const MOD: Int = 1_000_000_007;
const INF: Int = 1_000_000_000;
const YESNO: [&'static str; 2] = ["Yes", "No"];

pub struct Input {
  words: std::collections::VecDeque<String>,
}
impl Input {
  pub fn new() -> Self {
    use std::io::prelude::*;
    let mut stdin = std::io::stdin();
    let mut input = String::new();
    stdin.read_to_string(&mut input).unwrap();
    let words = input.split_ascii_whitespace().map(str::to_string).collect();
    Self { words }
  }

  pub fn read<T: std::str::FromStr>(&mut self) -> T {
    let res = self.words.pop_front().unwrap().parse();
    if let Ok(r) = res {
      r
    } else {
      panic!("read() failed")
    }
  }
}

fn yes() { println!("{}", YESNO[0]); }
fn no() { println!("{}", YESNO[1]); }
fn yesno(c: bool) { println!("{}", if c { YESNO[0] } else { YESNO[1] }); }