#include #include using namespace std; using namespace atcoder; //using mint = modint1000000007; //const int mod = 1000000007; using mint = modint998244353; const int mod = 998244353; //const int INF = 1e9; //const long long LINF = 1e18; #define rep(i, n) for (int i = 0; i < (n); ++i) #define rep2(i,l,r)for(int i=(l);i<(r);++i) #define rrep(i, n) for (int i = (n-1); i >= 0; --i) #define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i) #define all(x) (x).begin(),(x).end() #define allR(x) (x).rbegin(),(x).rend() #define endl "\n" #define P pair template inline bool chmax(A& a, const B& b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(A& a, const B& b) { if (a > b) { a = b; return true; } return false; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); long long h, w, k; cin >> h >> w >> k; vectorx(k), y(k), v(k); rep(i, k) { cin >> x[i] >> y[i] >> v[i]; x[i]--, y[i]--; } mint inv2 = ((mint)2).inv(); mint ans = 0; rep(i, k) { long long f0 = x[i] - y[i] + 1; long long fx = x[i] + 1; long long fw = x[i] - (w - 1 - y[i]) + 1; mint sub = 0; if (f0 < 0) sub += (1 + fx) * fx * inv2; else sub += (f0 + fx) * (fx - f0 + 1) * inv2; if (fw < 0) sub += (1 + fx) * fx * inv2; else sub += (fw + fx) * (fx - fw + 1) * inv2; sub -= fx; ans += sub * v[i]; } cout << ans.val() << endl; return 0; }