#include <bits/stdc++.h>

#define debug(...) 42;
#ifdef LOCAL
#include "debug.h"
#endif

using namespace std;
#define V vector
#define fi first
#define se second
#define mp make_pair
#define sz(a) ((int)a.size())
#define all(a) a.begin(), a.end()
#define F(i, l, r) for (int i = l; i < r; ++i)
#define R(i, l, r) for (int i = r-1; i >= l; --i)
typedef long long LL;
typedef double DB;
typedef pair<int, int> PII;
template<typename T> bool setmin(T &a, T b) { return (a > b ? a = b, 1 : 0); }
template<typename T> bool setmax(T &a, T b) { return (a < b ? a = b, 1 : 0); }
// mt19937_64 rng {chrono::steady_clock::now().time_since_epoch().count()};

/* -------------Main code------------- */
void solve() {
    int n, m; cin >> n >> m;
    vector<int> a(n), b(m);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    for (int i = 0; i < m; i++) {
        cin >> b[i];
    }

    long long op = 0;
    for (int i = 0; i < m; i++) {
        if (b[i] < a[n - m + i]) {
            cout << -1 << '\n';
            return;
        }
        op += b[i] - a[n - m + i];
    }

    if (op > n - m) {
        cout << -1 << '\n';
        return;
    }

    vector<int> ans; ans.reserve(n - m);
    multiset<int> pre, suf;

    for (int i = 0; i < n - m; i++) {
        pre.insert(a[i]);
    }
    for (int i = n - m; i < n; i++) {
        suf.insert(a[i]);
    }

    int left = n - m;
    while (true) {
        if (pre.empty()) break;
        if (left == op) break;
        int remove = *pre.begin(); pre.extract(remove);
        ans.push_back(remove);
        remove += 1;
        pre.insert(remove);
        if (!suf.empty()) {
            int head = *suf.begin(), tail = *pre.rbegin();
            if (head < tail) {
                // assert(tail - head == 1);
                suf.extract(head); suf.insert(tail); --op;
                pre.extract(tail); pre.insert(head);
            }
        }
        pre.erase(pre.begin());
        --left;
    }

    if (op != left) {
        cout << -1 << '\n';
        return;
    }

    auto cur = vector<int>(all(suf));
    for (int i = 0; i < m; i++) {
        if (cur[i] > b[i]) {
            cout << -1 << '\n';
            return;
        }
        for (int j = 0, d = cur[i]; j < b[i] - cur[i]; j++) {
            ans.push_back(d++);
        }
    }

    cout << n - m << '\n';
    for (int i : ans) cout << i << ' ';
    cout << '\n';
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    int tt; cin >> tt;
    while (tt--) solve();

    return 0;
}