//Linkwish's code
#include<bits/stdc++.h>
#define endl '\n'
#define si inline
#define fi first
#define se second
using namespace std;
typedef long long ll;typedef __int128 li;typedef long double ld;
typedef pair<int,int> pii;typedef pair<ll,ll> pll;
typedef const int ci;typedef const ll cl;ci iinf=1e9;cl linf=LLONG_MAX;
template<typename T>si bool gmax(T &x,const T y){if(x<y)return x=y,1;return 0;}
template<typename T>si bool gmin(T &x,const T y){if(y<x)return x=y,1;return 0;}

namespace LinkWish{

    ci N=(1<<19),M=N,mod=998244353;

    si int qpow(int x,int y){
        int res=1;
        for(;y;x=1ll*x*x%mod,y>>=1)if(y&1)res=1ll*res*x%mod;
        return res;
    }
    
    si int GMod(ci x){return x>mod?x-mod:x;}
    
    int lena=N,lenb=N;
    int A[M],B[M];
    int lg,lim,P[M];
    si void calclim(){lim=1<<(lg=__lg(lena+lenb)+1);}
    si void Init(){
        calclim();
        for(int i=0,j=1,w;i<lg;i++){
            w=qpow(3,(mod-1)>>(i+1)),P[j++]=1;
            for(;j<(2<<i);j++)P[j]=1ll*P[j-1]*w%mod;
        }
    }
    
    si void DIF(int *a){
        for(int i=lg-1,len=lim>>1;~i;i--,len>>=1){
            for(int j=0;j<lim;j+=(len<<1)){
                for(int k=j,x,y,cur=len;k<j+len;k++,cur++){
                    x=a[k],y=a[k+len];
                    a[k]=GMod(x+y),a[k+len]=1ll*(x-y+mod)*P[cur]%mod;
                }
            }
        }
    }
    si void DIT(int *a){
        for(int i=0,len=1;i<lg;i++,len<<=1){
            for(int j=0;j<lim;j+=(len<<1)){
                for(int k=j,x,y,cur=len;k<j+len;k++,cur++){
                    x=a[k],y=1ll*a[k+len]*P[cur]%mod;
                    a[k]=GMod(x+y),a[k+len]=GMod(x-y+mod);
                }
            }
        }
        reverse(a+1,a+lim);
        for(int i=0,inv=qpow(lim,mod-2);i<lim;i++)a[i]=1ll*a[i]*inv%mod;
    }

    int n=400003;
    vector<int> e[N];

    int fac[N],inv[N];
    si void init(){
        fac[0]=1;for(int i=1;i<=n;i++)fac[i]=1ll*fac[i-1]*i%mod;
        inv[n]=qpow(fac[n],mod-2);for(int i=n-1;~i;i--)inv[i]=1ll*inv[i+1]*(i+1)%mod;
    }
    si int C(int x,int y){
        if(x<0||y<0||x<y)return 0;
        return 1ll*fac[x]*inv[y]%mod*inv[x-y]%mod;
    }

    int sz[N],cnt[N];
    void dfs(int x,int fa){
        sz[x]=1;
        for(int to:e[x])if(to!=fa)dfs(to,x),sz[x]+=sz[to];
        cnt[sz[x]]++,cnt[n-sz[x]]++;
    }
    
    void mian(){
        init();

		int t; scanf("%d", &t); while (t--) {
			int n, m; scanf("%d %d", &n, &m);


			lena=n*m, lenb = n*m, Init();
			// for(int i=0;i<=n;i++){
			//     A[i]=inv[i];
			//     B[i]=1ll*cnt[n-i+1]*fac[n-i+1]%mod;
			// }

			static int w[200005], a[200005];
			for (int i = 0; i <= n * m; i++) w[i] = 0;
			for (int i = 1; i <= n * m; i++) scanf("%d", &a[i]);
			sort(a + 1, a + 1 + n * m);
			for (int i = 0; i <= n; i++) for (int j = 0; j <= m; j++) {
				if (i == n && j == m) continue;
				if ((n + m - i - j) & 1) w[i * j] = (w[i * j] + 1ll * fac[n] * inv[i] % mod * inv[n - i] % mod * fac[m] % mod * inv[j] % mod * inv[m - j]) % mod;
				else w[i * j] = (w[i * j] + 1ll * (mod - fac[n]) * inv[i] % mod * inv[n - i] % mod * fac[m] % mod * inv[j] % mod * inv[m - j]) % mod;
			}
            for (int i = 0; i < lim; i++) A[i] = 0, B[i] = 0;
            for (int i = 0; i <= n * m; i++) A[i] = 1ll * w[i] * fac[i] % mod;
            for (int i = 0; i <= n * m; i++) B[i] = inv[i];
            reverse(B, B + n * m + 1);
            // for (int i = 0; i <= n * m; i++) printf("%d%c", w[i], " \n"[i == n * m]);



			// A[0] = 0; for (int i = 1; i <= n; i++) A[i] = 1ll * inv[i - 1] * inv[i - 1] % mod;
			// B[0] = 0; for (int i = 1; i < m; i++) B[i] = 1ll * inv[i - 1] * inv[i - 1] % mod;

			DIF(A),DIF(B);
			for(int i=0;i<lim;i++)A[i]=1ll*A[i]*B[i]%mod;
			DIT(A);

            for (int i = 0; i <= n*m; i++) w[i] = 1ll * A[i + n * m] * inv[i] % mod;
            for (int i = 0; i <= n*m; i++) w[i] = 1ll * w[i] * fac[i] % mod * fac[n*m - i] % mod;
            // for (int i = 0; i <= n * m; i++) printf("%d%c", w[i], " \n"[i == n * m]);
            for (int i = 0; i < n * m; i++) w[i] = (w[i] + mod - w[i + 1]) % mod;
            int ans = 0;
            for (int i = 0; i < n * m; i++) ans = (ans + 1ll * w[i] * a[n * m-  i]) % mod;
            printf("%d\n", ans);
			
			// memset(A, 0, sizeof A); memset(B, 0, sizeof B);
			// A[0] = 0; for (int i = 1; i <= n; i++) A[i] = 1ll * inv[i] * (i == 1 ? 0 : inv[i - 2]) % mod;
			// B[0] = 0; for (int i = 1; i < m; i++) B[i] = 1ll * inv[i] * (i == 1 ? 0 : inv[i - 2]) % mod;
			// // for (int i = 1; i <= n; i++) printf("@ %d\n", A[i]);
			// // for (int i = 1; i < m; i++) printf("# %d\n", B[i]);

			// DIF(A),DIF(B);
			// for(int i=0;i<lim;i++)A[i]=1ll*A[i]*B[i]%mod;
			// DIT(A);

			// // for (int i = 2; i < n + m; i++) printf("! %d %lld\n", A[i], 1ll * fac[i - 2] * fac[i - 2] % mod * A[i] % mod);
			// for (int i = 2; i < n + m; i++) ans = (ans + 1ll * (mod - fac[i - 2]) * fac[i - 2] % mod * A[i]) % mod;

			// printf("%d\n", (ans + 2) % mod);
		}
    }
}

signed main(){
    // #ifndef ONLINE_JUDGE
    // assert(freopen("in.in","r",stdin));
    // #endif
    // ios::sync_with_stdio(0);
    // cin.tie(0),cout.tie(0);   
    LinkWish::mian();
    return 0;
}