#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);