#include <bits/stdc++.h>
using namespace std;
using namespace chrono;

using ll = long long;
using ull = unsigned long long;

string to_string(const string &s) {
  return '"' + s + '"';
}

string to_string(bool b) {
  return b ? "true" : "false";
}

template <typename A, typename B>
string to_string(const pair<A, B> &p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename T>
string to_string(const T &v) {
  string s = "{";
  bool first = true;
  for (const auto &it : v) {
    if (!first)
      s += ", ";
    else
      first = false;
    s += to_string(it);
  }
  return s += "}";
}

void debug_out() {
  cerr << "\n";
}

template <typename T, typename... Args>
void debug_out(const T &first, const Args&... rest) {
  cerr << to_string(first) << " ";
  debug_out(rest...);
}

#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

auto startTime = high_resolution_clock::now();
int get_time() {
  auto stopTime = chrono::high_resolution_clock::now();
  auto duration = duration_cast<milliseconds>(stopTime - startTime);
  return duration.count(); // in ms
}

void solve() {
  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  vector<int> b(m);

  for (int i = 0; i < n; ++i) {
    cin >> a[i];
  }

  ll sb = 0;
  for (int i = 0; i < m; ++i) {
    cin >> b[i];
    sb += b[i];
  }

  if (n < m) {
    cout << "-1\n";
    return;
  }

  sort(a.begin(), a.end());
  sort(b.begin(), b.end());

  ll sa = 0;
  for (int i = a.size() - b.size(), j = 0; i < a.size(); ++i, ++j) {
    sa += a[i];
    if (a[i] > b[j]) {
      cout << -1 << "\n";
      return;
    }
  }

  if (n - (sb - sa) < m) {
    cout << -1 << "\n";
    return;
  }

  set<pair<int, int>> s, s2;
  for (int i = 0; i < a.size() - b.size(); ++i)
    s.insert({a[i], i});

  for (int i = a.size() - b.size(); i < n; ++i)
    s2.insert({a[i], i});

  int rem = (n - (sb - sa)) - m, k = 0;
  vector<int> mv;
  for (int i = a.size() - b.size(), j = 0; i < a.size(); ++i, ++j) {
    while (rem > 0 && s.begin()->first + 1 <= s2.begin()->first) {
      mv.push_back(s.begin()->first);
      --rem;
      s.insert({s.begin()->first + 1, s.begin()->second});
      s.erase(s.begin());
      s.erase(s.begin());
    }

    s2.erase({a[i], i});
    while (a[i] < b[j]) {
      ++k;
      mv.push_back(a[i]);
      s.erase(s.begin());
      ++a[i];
    }
    s2.insert({a[i], i});
  }

  while (rem > 0 && s.begin()->first + 1 <= s2.begin()->first) {
    mv.push_back(s.begin()->first);
    --rem;
    s.insert({s.begin()->first + 1, s.begin()->second});
    s.erase(s.begin());
    s.erase(s.begin());
  }

  if (rem > 0) {
    cout << "-1" << "\n";
    return;
  }

  cout << mv.size() << '\n';
  for (auto it : mv)
    cout << it << " ";
  cout << '\n';
}

int main() {
  cin.tie(NULL);
  ios_base::sync_with_stdio(false);

  int t = 1;
  cin >> t;
  while (t--)
    solve();

  return 0;
}