#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=300010;
int a[N],b[N];
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin>>T;
    while(T--){
        int n,m;
        cin>>n>>m;
        for(int i=1;i<=n;i++)cin>>a[i];
        for(int i=1;i<=m;i++)cin>>b[i];
        sort(a+1,a+1+n);
        sort(b+1,b+1+m);
        int diff=0;
        bool flag=true;
        for(int i=m;i>=1;i--){
            diff+=b[i]-a[i+n-m];
            if(b[i]-a[i+n-m]<0)flag=false;
        }
        if(!flag || diff>n-m)cout<<"-1\n";
        else{
            int need_waste=n-m-diff;
            vector<int>ans;
            multiset<int>ms;
            for(int i=1;i<=n;i++)ms.insert(a[i]);
            int bounded_waste=0,max_waste=0;
            int l1=0,r1=0,l2=0,r2=0;
            for(int i=1;i<=n;i++){
                if(a[i]<a[n-m+1]-1){
                    max_waste++;
                    bounded_waste++;
                }
                if(a[i]==a[n-m+1]-1){
                    if(!l1)l1=i;
                    r1=i;
                }
                else if(a[i]==a[n-m+1]){
                    if(!l2)l2=i;
                    r2=i;
                }
            }
            int r=r2;
            int l;
            if(l1){
                l=(l1+r1+2)/2;
                max_waste+=l-l1;
                bounded_waste+=l-l1;
            }
            else l=l2;
            if(b[1]!=a[n-m+1]&&r-n+m<n-m-l+1)max_waste+=(n-m-l+1-r+n-m+1)/2;
            //cout<<"DAMN   "<<need_waste<<" "<<bounded_waste<<"\n";
            if(need_waste>max_waste)cout<<"-1\n";
            else{
                cout<<n-m<<"\n";
                for(int i=1;i<=min(bounded_waste,need_waste);i++){
                    int rm=*(ms.begin());
                    ms.erase(ms.find(rm));
                    cout<<rm<<" ";
                    ms.insert(rm+1);
                    int mn=*(ms.begin());
                    ms.erase(ms.find(mn));
                }
                if(need_waste>bounded_waste){
                    for(int i=1;i<=r-n+m+need_waste-bounded_waste;i++){
                        cout<<a[n-m+1]<<" ";
                    }
                }
                for(int i=1;i<=m;i++){
                    for(int j=a[n-m+i];j+1<=b[i];j++){
                        if(need_waste<=bounded_waste||j>a[n-m+1])cout<<j<<" ";
                    }
                }
                cout<<"\n";
            }
            ms.clear();
        }
    }
    return 0;
}