#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
typedef long long ull;
typedef unsigned long long uull;
typedef pair<int, int> PII;
mt19937 rnd1(random_device{}());
mt19937_64 rnd2(random_device{}());
uniform_int_distribution<int> dist1(0,2e18);    //定义dist1为0——100的随机整数
uniform_real_distribution<double> dist2(-10,10);    //定义dist2为-10——10的随机浮点数
//#define mp make_pair
//fflush(stdout);
inline void print(__int128 x){//输出模板 
    if(x<0){
        putchar('-');
        x=-x;
    }
    if(x>9) print(x/10);
    putchar(x%10+'0');
}
inline int read()
{
    int X = 0;
    bool flag = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9')
    {
        if (ch == '-')
            flag = 0;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        X = (X << 1) + (X << 3) + ch - '0';
        ch = getchar();
    }
    if (flag)
        return X;
    return ~(X - 1);
}
const ull mod = 1e9+7,INF = 2e18;
ull qpow(ull a, ull b)
{
    ull res = 1;
    a %= mod;
    assert(b >= 0);
    for (; b; b >>= 1)
    {
        if (b & 1)
            res = res * a % mod;
        a = a * a % mod;
    }
    return res;
}
inline int gcd(int a, int b) { return b == 0 ? a : gcd(b, a % b); }
inline int lcm(int a, int b) { return a / gcd(a, b) * b; }
const int N = 300010,M = 400010;

int a[N],b[N],ans[N];
priority_queue<int,vector<int>,greater<int> > q;

void solve()
{
    while(q.size()) q.pop();
    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 s = 0,flag = 1,idx = 0;
    for(int i=1;i<=m;i++)
        if(b[i]>=a[n-m+i])
        {
            int t = b[i]-a[n-m+i];
            s += t;
        }
        else 
        {
            cout<<-1<<endl;
            return;
        }
    int nd = n-m-s;
    if(nd<0)
    {
        cout<<-1<<endl;
        return;
    }
    for(int i=1;i<=nd;i++) q.push(a[i]);
    int maxi = 0;
    while(q.size())
    {
        int t = q.top();
        ans[++idx] = t;
        q.pop(),q.push(t+1);
        maxi = max(maxi,t+1);
        q.pop();
    }
    for(int i=1;i<=m;i++)
    {
        int t = b[i]-a[n-m+i];
        for(int j=1;j<=t;j++) ans[++idx] = a[n-m+i],a[n-m+i]++;
    }
        
    if(maxi>b[1]) cout<<-1<<endl;
    else 
    {
        cout<<idx<<endl;
        for(int i=1;i<=idx;i++) cout<<ans[i]<<' ';
        cout<<endl;
    }
}

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