#define MD 998244353
ll@H,@W,@K;
mint z;
rep(K){
  ll@x,@y,@v;
  z+=v*(
    x*x
    -max(0,(x-y))*(x-y+1)/2
    -max(0,(x-(W+1-y)))*(x-(W+1-y)+1)/2
  );
}
wt(z);