#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using vll = vector<long long>;
using vvll = vector<vector<long long>>;
using vs = vector<string>;
using vb = vector<bool>;
using vvb = vector<vector<bool>>;
#define lln \
  ll n;     \
  cin >> n;
#define REP(i, n) for (long long i = 0; i < n; i++)
#define REPIN(v, n) \
  for (long long i = 0; i < n; i++) cin >> v[i];
ll gcd(ll x, ll y) { return (x % y) ? gcd(y, x % y) : y; }
ll lcm(ll x, ll y) { return x / gcd(x, y) * y; }

int main() {
  ll H, W, K;
  cin >> H >> W >> K;
  vvll xyv(K, {0, 0, 0});
  REP(i, K) { cin >> xyv[i][0] >> xyv[i][1] >> xyv[i][2]; }
  ll mod = 998244353, cnt = 0;
  REP(i, H) {
    REP(j, W) {
      REP(k, K) {
        if ((i + 1) + (j + 1) <= xyv[k][0] + xyv[k][1] &&
            (i + 1) - (j + 1) <= xyv[k][0] - xyv[k][1]) {
          cnt += xyv[k][2];
          cnt %= mod;
        }
      }
    }
  }
  cout << cnt % mod << endl;
}