#include using namespace std; typedef signed long long ll; #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x<(to);x++) #define FORR(x,arr) for(auto& x:arr) #define FORR2(x,y,arr) for(auto& [x,y]:arr) #define ALL(a) (a.begin()),(a.end()) #define ZERO(a) memset(a,0,sizeof(a)) #define MINUS(a) memset(a,0xff,sizeof(a)) template bool chmax(T &a, const T &b) { if(a bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;} //------------------------------------------------------- int T,H,W; const ll mo=998244353; ll from[3]; ll to[3]; ll comb(ll N_, ll C_) { const int NUM_=400001; static ll fact[NUM_+1],factr[NUM_+1],inv[NUM_+1]; if (fact[0]==0) { inv[1]=fact[0]=factr[0]=1; for (int i=2;i<=NUM_;++i) inv[i] = inv[mo % i] * (mo - mo / i) % mo; for (int i=1;i<=NUM_;++i) fact[i]=fact[i-1]*i%mo, factr[i]=factr[i-1]*inv[i]%mo; } if(C_<0 || C_>N_) return 0; return factr[C_]*fact[N_]%mo*factr[N_-C_]%mo; } void solve() { int i,j,k,l,r,x,y; string s; cin>>T; while(T--) { cin>>W>>H; from[0]=1; from[1]=from[2]=0; FOR(y,H+1) { ZERO(to); to[0]=(from[0]+from[1]+from[2])%mo; to[1]=(W*from[0]+(W-1)*from[1]+(W-2)*from[2])%mo; to[2]+=from[0]*(comb(W,2)-W); to[2]+=from[1]*(comb(W-1,2)-(W-2)); to[2]+=from[2]*(comb(W-2,2)-(W-4)); to[2]=((to[2]%mo)+mo)%mo; swap(from,to); } cout<