// Coded by hjxddl
#include <bits/stdc++.h>
#define ll long long
#define db double
const int N = 2e5 + 5;
struct left_tree {
    ll dist, val;
    int ls, rs;
    left_tree() :
        dist(0), val(0), ls(0), rs(0) {
    }
    bool operator<(const left_tree &A) {
        return val < A.val;
    }
};
int rt;
int merge(int x, int y, std::vector<left_tree> &t) {
    if (!x || !y) return x | y;
    if (t[y] < t[x]) std::swap(x, y);
    t[x].rs = merge(t[x].rs, y, t);
    if (t[t[x].ls].dist < t[t[x].rs].dist)
        std::swap(t[x].ls, t[x].rs);
    t[x].dist = t[t[x].rs].dist + 1;
    return x;
}
void solve() {
    ll n, m;
    std::cin >> n >> m;
    std::vector<ll> a(n + 5), b(m + 5), ans(m + 5);
    std::vector<left_tree> t(n + 5), t1(n + 5);
    for (int i = 1; i <= n; i++)
        std::cin >> a[i];
    for (int i = 1; i <= m; i++)
        std::cin >> b[i];
    std::sort(a.begin() + 1, a.begin() + 1 + n);
    std::sort(b.begin() + 1, b.begin() + 1 + m);
    for (int i = n - m + 1, j = 1; i <= n; i++, j++)
        ans[j] = a[i];
    ll sum = 0;
    for (int i = 1; i <= m; i++) {
        sum += b[i] - ans[i];
        if (ans[i] > b[i]) {
            std::cout << -1 << '\n';
            return;
        }
    }
    rt = 1;
    for (int i = 1; i <= n; i++)
        t[i].val = t1[i].val = a[i];
    for (int i = 2; i <= n; i++)
        rt = merge(rt, i, t);
    int rt1 = n - m + 1;
    for (int i = n - m + 2; i <= n; i++)
        rt1 = merge(rt1, i, t1);
    ll rest = n - m;
    std::queue<ll> q;
    while (sum < rest) {
        int x = rt;
        rt = merge(t[rt].ls, t[rt].rs, t);
        q.push(t[x].val);
        t[x].val++;
        t[x].ls = t[x].rs = t[x].dist = 0;
        rt = merge(rt, x, t);
        rt = merge(t[rt].ls, t[rt].rs, t);
        rest--;
        if (t[x].val > t1[rt1].val) {
            sum = sum + t1[rt1].val - t[x].val;
            t1[x].val = t[x].val;
            rt1 = merge(t1[rt1].ls, t1[rt1].rs, t1);
            rt1 = merge(rt1, x, t1);
            if (t1[rt1].val > b[1]) {
                std::cout << -1 << '\n';
                return;
            }
        }
    }
    if (sum > rest) {
        std::cout << -1 << '\n';
        return;
    }
    std::cout << n - m << '\n';
    while (q.size()) {
        std::cout << q.front() << ' ';
        q.pop();
    }
    // std::cout << "\n\n\n";
    for (int i = 1; i <= m; i++) {
        for (ll j = t1[rt1].val; j < b[i]; j++) {
            std::cout << j << ' ';
        }
        rt1 = merge(t1[rt1].ls, t1[rt1].rs, t1);
    }
    std::cout << '\n';
}
int main() {
    std::ios::sync_with_stdio(0);
    std::cin.tie(0), std::cout.tie(0);
    int t = 1;
    std::cin >> t;
    while (t--) {
        solve();
    }
    std::cout << std::flush;
    // system("pause");
}