#include<bits/stdc++.h>
#define rep(i,l,r) for(int i=l;i<=r;++i)
#define repd(i,l,r) for(int i=l;i>=r;--i)
using namespace std;
using ll =long long;
using LL =long long;
const int N=1e6+50;
const int mod=998244353;
#define int long long
#define pb push_back
LL getmi(LL a,LL x)
{
    LL rt=1;
    while(x)
    {
        if(x&1) rt=rt*a%mod;
        a=a*a%mod,x>>=1;
    }
    return rt;
}
int n,m,len,bin[N];
ll t[N];
LL lim,a[N],b[N],c[N],G[N],A0[N],A[N],B[N],inv[N];  
ll f[N],F[N],g[N],h[N];        
int getint()
{
    char ch;
    while(!isdigit(ch=getchar()));
    int x=ch-48;
    while(isdigit(ch=getchar())) x=x*10+ch-48;
    return x;
}


void FFT(LL a[],int len,int tp)
{
    rep(i,0,len-1) bin[i]=bin[i>>1]>>1|((i&1)*(len>>1));
    rep(i,0,len-1) if(i<bin[i]) swap(a[i],a[bin[i]]);
    for(int i=1; i<len; i<<=1)
    {
        LL wn=getmi(3,(mod-1)/(i<<1));
        if(tp==-1) wn=getmi(wn,mod-2);
        for(int j=0; j<len; j+=i<<1)
        {
            LL w=1,x,y;
            rep(k,0,i-1)
            {
                x=a[j+k],y=a[i+j+k]*w%mod,w=w*wn%mod;
                a[j+k]=(x+y)%mod,a[i+j+k]=(x-y+mod)%mod;
            }
        }
    }
    if(tp==-1)
    {
        LL x=getmi(len,mod-2);
        rep(i,0,len-1) a[i]=a[i]*x%mod;
    }
}
ll invv(ll x)
{
    return getmi(x,mod-2);
}
ll fac[N],ifac[N];
void init(ll nn=N-5)
{
    fac[0]=fac[1]=ifac[0]=ifac[1]=1;
    rep(i,2,nn) fac[i]=fac[i-1]*i%mod;
    ifac[nn]=invv(fac[nn]);
    repd(i,nn,2) ifac[i-1]=ifac[i]*i%mod;
}      
ll C(ll n,ll m)
{
    return fac[n]*ifac[m]*ifac[n-m]%mod;
}
void solve()
{
    cin>>n>>m;
    rep(i,1,n*m) cin>>t[i];
    //cout<<ifac[0]<<"\n";
    sort(t+1,t+n*m+1);
    ll len=1;
    for(len=1;len<=2*n*m;len<<=1);
    len<<=1;
    rep(i,0,len<<1)g[i]=f[i]=h[i]=0;
    g[0]=0;
    rep(i,1,m*n)g[i]=t[i]*fac[i-1]%mod;
    //rep(i,1,n*m)g[i]=1;
   // rep(i,n*m+1,2*n*m)g[i]=0;
    rep(i,0,m*n)h[i]=ifac[n*m-i];
    //rep(i,n*m+1,2*n*m)h[i]=0;
    rep(i,1,len)f[i]=0;
    //rep(i,1,2*m*n) cout<<i<<" "<<g[i]<<"\n";
    FFT(g,len,1);FFT(h,len,1);
    rep(i,0,len) f[i]=1LL*g[i]*h[i]%mod;
    FFT(f,len,-1);
    rep(i,0,n*m)F[i]=f[n*m+i];
    //rep(i,1,2*m*n) cout<<i<<" "<<f[i]<<"\n";
    ll ans=0;
    rep(c,0,n) rep(d,0,m)
    {
        ll k=n*m-d*c,tmp=0;
        tmp=C(n,c)*C(m,d)%mod;
        tmp=tmp*fac[n*m-k]%mod*(k)%mod;
        tmp=tmp*F[k]%mod;
        if((n+m-c-d)%2) ans=(ans+tmp)%mod;
        else ans=(ans+mod-tmp)%mod;
    }
    cout<<ans<<"\n";



}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    int t=1;
    init();
    cin>>t;
    while(t--)solve();
    return 0;
}