#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<ll> poly;
const ll M=998244353;
ll qpow(ll a,ll b){
    a%=M;
    ll ans=1;
    while(b){
        if(b&1)ans=ans*a%M;
        a=a*a%M;
        b>>=1;
    }
    return ans;
}

const ll g=3,rg=qpow(g,M-2);
vector<int> rev;
void NTT(poly& f,int op){
    for(int i=0;i<f.size();i++)if(i<rev[i])swap(f[i],f[rev[i]]);
    for(int m=1;m<f.size();m<<=1){
        ll gn=qpow(op==1?g:rg,(M-1)/(m<<1));
        for(int j=0;j<f.size();j+=(m<<1)){
            ll w=1;
            for(int k=0;k<m;k++,w=w*gn%M){
                ll x=f[j+k],y=w*f[j+k+m]%M;
                f[j+k]=(x+y)%M;
                f[j+k+m]=(x-y+M)%M;
            }
        }
    }
    if(op==-1){
        ll inv=qpow(f.size(),M-2);
        for(int i=0;i<f.size();i++)f[i]=f[i]*inv%M;
    }
}

poly operator*(poly f,poly g){
    int len=f.size()+g.size()-1;
    int c=0;for(int t=1;t<len;t<<=1)c++;
    int deg=(1<<c);rev.resize(deg);rev[0]=0;
    for(int i=1;i<deg;i++)rev[i]=(rev[i>>1]>>1)+((i&1)<<(c-1));
    f.resize(deg);g.resize(deg);NTT(f,1);NTT(g,1);
    for(int i=0;i<deg;i++)f[i]=f[i]*g[i]%M;
    NTT(f,-1);f.resize(len);
    return f;
}

poly qpow(poly f,ll b){
    poly ans={1};
    while(b){
        if(b&1)ans=ans*f;
        f=f*f;
        b>>=1;
    }
    return ans;
}

const int N=200000;
ll fac[N],ifac[N];
void init(){
    fac[0]=1;
    for(int i=1;i<N;i++)fac[i]=fac[i-1]*i%M;
    ifac[N-1]=qpow(fac[N-1],M-2);
    for(int i=N-2;i>=0;i--)ifac[i]=ifac[i+1]*(i+1)%M;
}

ll C(ll a,ll b){
    if(a<b||a<0)return 0;
    return fac[a]*ifac[b]%M*ifac[a-b]%M;
}

void solve(){
    int n,m;cin>>n>>m;
    vector<ll> a(n*m);
    for(int i=0;i<n*m;i++)cin>>a[i];
    sort(a.begin(),a.end());

    poly f(n*m+1);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            int sgn=(n+m-i-j)%2==0?1:M-1;
            f[i*j]=(f[i*j]+fac[i*j]*C(n,i)%M*C(m,j)%M*sgn)%M;
        }
    }

    // for(int i=0;i<f.size();i++)cout<<f[i]<<" ";
    // cout<<"\n";

    poly g(n*m+1);
    for(int i=0;i<=n*m;i++)g[i]=ifac[n*m-i];
    f=f*g;
    f=poly(f.begin()+n*m,f.end());
    for(int i=0;i<f.size();i++)f[i]=f[i]*ifac[i]%M;
    f[0]=0;

    // for(int i=0;i<f.size();i++)cout<<f[i]<<" ";
    // cout<<"\n";

    int l=0,r;
    vector<pair<ll,ll>> v;
    while(l<n*m){
        r=l;
        while(r<n*m&&a[r]==a[l])r++;r--;
        
        v.push_back({a[l],f[n*m-l]*fac[n*m-l]%M*fac[l]%M});
        l=r+1;
    }
    // for(int i=0;i<v.size();i++)cout<<v[i].first<<":"<<v[i].second<<"\n";
    for(int i=0;i+1<v.size();i++)v[i].second=(v[i].second-v[i+1].second+M)%M;
    ll ans=0;
    for(int i=0;i<v.size();i++){
        ans=(ans+v[i].first*v[i].second)%M;
        // cout<<v[i].first<<":"<<v[i].second<<"\n";
    }
    cout<<ans<<"\n";
    
}

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