#![allow(unused_imports, unused_macros)]
use myu2::*;
use std::cmp::*;
use std::collections::*;
use std::io::Read;

fn main() {
    input! {
        h: i64, w: i64, k: i64,
        xyv: [(i64, i64, i64); k]
    }

    let mut ans: i64 = 0;
    for i in 0..h {
        for j in 0..w {
            for ki in 0..k {
                let (mut x, mut y, v) = xyv[ki as usize];
                x -= 1;
                y -= 1;
                if x + y >= i + j && x - y >= i - j {
                    ans += v;
                    ans %= 998244353;
                }
            }
        }
    }
    println!("{}", ans);
}

// lib

// util
#[macro_use]
pub mod myu2 {
    // input
    #[macro_export]
    macro_rules! input { ($($r:tt)*) => { let mut bytes = std::io::Read::bytes(std::io::BufReader::new(std::io::stdin())); let mut next = move |is_word: bool| -> String{if is_word { bytes.by_ref().map(|r|r.unwrap() as char).skip_while(|c|c.is_whitespace()).take_while(|c|!c.is_whitespace()).collect() } else { bytes.by_ref().map(|r|r.unwrap() as char).skip_while(|c| c == &'\n').take_while(|c| c != &'\n').collect() } }; input_inner!{next, $($r)*}; }; }
    #[macro_export]
    macro_rules! input_inner { ($next:expr) => {}; ($next:expr, ) => {}; ($next:expr, static $var:ident : $t:tt $($rest:tt)*) => { $var = read_value!($next, $t); input_inner!{$next $($rest)*} }; ($next:expr, mut $var:ident : $t:tt $($rest:tt)*) => { let mut $var = read_value!($next, $t); input_inner!{$next $($rest)*} }; ($next:expr, $var:ident : $t:tt $($rest:tt)*) => { let $var = read_value!($next, $t); input_inner!{$next $($rest)*} }; }
    #[macro_export]
    macro_rules! read_value { ($next:expr, ( $($t:tt),* )) => { ( $(read_value!($next, $t)),* ) }; ($next:expr, [ $t:tt ; all ]) => { { let mut str = $next(false); str.split_whitespace().map(|it| it.parse::<$t>().unwrap()).collect::<Vec<_>>() } }; ($next:expr, [ $t:tt ; $len:expr ]) => { (0..$len as usize).map(|_| read_value!($next, $t)).collect::<Vec<_>>() }; ($next:expr, chars) => { read_value!($next, String).chars().collect::<Vec<char>>() }; ($next:expr, lines) => { { let mut vec = Vec::new(); let mut str = $next(false); while str != "" { vec.push(str); str = $next(false); } vec } }; ($next:expr, line) => { $next(false) }; ($next:expr, usize1) => { read_value!($next, usize) - 1 }; ($next:expr, $t:ty) => { $next(true).parse::<$t>().expect("Parse error") }; }
    // min, max
    #[macro_export]
    macro_rules! min { ($a:expr $(,)*) => {{ $a }}; ($a:expr, $b:expr $(,)*) => {{ std::cmp::min($a, $b) }}; ($a:expr, $($rest:expr),+ $(,)*) => {{ std::cmp::min($a, min!($($rest),+)) }}; }
    #[macro_export]
    macro_rules! max { ($a:expr $(,)*) => {{ $a }}; ($a:expr, $b:expr $(,)*) => {{ std::cmp::max($a, $b) }}; ($a:expr, $($rest:expr),+ $(,)*) => {{ std::cmp::max($a, max!($($rest),+)) }}; }
    // chmin, chmax
    #[macro_export]
    macro_rules! chmin { ($base:expr, $($cmps:expr),+ $(,)*) => {{ let cmp_min = min!($($cmps),+); if $base > cmp_min { $base = cmp_min; true } else { false } }}; }
    #[macro_export]
    macro_rules! chmax { ($base:expr, $($cmps:expr),+ $(,)*) => {{ let cmp_max = max!($($cmps),+); if $base < cmp_max { $base = cmp_max; true } else { false } }}; }
}