#include <bits/stdc++.h>
using namespace std;
 
#define fi first
#define se second
#define pb push_back
using vi = vector <int>;
using ll = long long;
using vl = vector <ll>;
using pii = pair <int, int>;
const ll mod = 998244353;
//~ const ll mod = 1e9 + 7;
ll qpow(ll a, ll b, ll m = mod) { ll r = 1, t = a;
	for(; b; b /= 2) { if(b & 1) r = r * t % m; t = t * t % m; } return r; }

const int N = 2e5 + 11;

struct treasure {
	int x, y, v;
	bool operator <(const treasure &t) {
		return pii{x, y} < pii(t.x, t.y);
	}
}t[N];

ll b[N];
void update(int p, int v) {
	for(int i = p; i < N; i += i & (-i))
		b[i] += v;
}
ll query(int p) {
	ll r = 0;
	for(int i = p; i; i -= i & (-i))
		r += b[i];
	return r;
}

int main() {
	ios::sync_with_stdio(0);
	int n, m, k; cin >> n >> m >> k;
	//~ for(int i = 0; i < n; i ++) {
		//~ int x, y, v; cin >> x >> y >> v;
		//~ t[i] = {x - y, x + y, v};
	//~ }
	
	//~ sort(t, t + n);
	//~ reverse(t, t + n);
	
	//~ ll ans = 0;
	//~ for(int i = 0; i < n; i ++) {
		//~ update(t[i].y, t[i].v);
		//~ ans += query(N - 1) - query(t[i].y - 1);
		//~ ans %= mod;
	//~ }
	
	//~ cout << ans << '\n';
	
	ll ans = 0;
	for(int i = 0; i < k; i ++) {
		ll x, y, v; cin >> x >> y >> v;
		
		ll cnt = x * x;
		ll l = y - (x - 1), r = y + (x - 1);
		
		if(l < 1)
			cnt -= (1 - l) * (1 - l + 1) / 2;
		
		if(r > m)
			cnt -= (r - m) * (r - m + 1) / 2;
		
		//~ cout << x << ' ' << y << ' ' << cnt << '\n';
		
		ans += cnt % mod * v;
		ans %= mod;
	}
	cout << ans << '\n';
}