#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

namespace {

void solve() {
  int n, m;
  scan(n, m);
  vector<int> a(n);
  scan(a);
  vector<int> b(m);
  scan(b);
  ranges::sort(a, greater{});
  ranges::sort(b, greater{});

  vector<int> ans;
  ans.reserve(n - m);
  auto op = [&](int x) {
    ++*ranges::lower_bound(a, x, greater{});
    a.pop_back();
    ans.push_back(x);
  };

  int64_t need = 0;
  for (int i : rep(m)) {
    if (b[i] < a[i]) {
      print(-1);
      return;
    }
    need += b[i] - a[i];
  }

  int l = 0;
  for (int k : rep(n - m)) {
    if (n - m - k < need) {
      print(-1);
      return;
    }
    if (n - m - k == need) {
      while (l < m && a[l] == b[l]) {
        ++l;
      }
      op(a[l]);
      --need;
    } else {
      op(a.back());
    }
  }

  if (a != b) {
    print(-1);
    return;
  }

  print(n - m);
  print(ans);
}

}  // namespace

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int t;
  scan(t);
  while (t--) {
    solve();
  }
}

#else  // __INCLUDE_LEVEL__

#include <bits/stdc++.h>

using namespace std;

namespace std {

template <class T1, class T2>
istream& operator>>(istream& is, pair<T1, T2>& p) {
  return is >> p.first >> p.second;
}

template <class... Ts>
istream& operator>>(istream& is, tuple<Ts...>& t) {
  return apply([&is](auto&... xs) -> istream& { return (is >> ... >> xs); }, t);
}

template <class R, enable_if_t<!is_convertible_v<R, string>>* = nullptr>
auto operator>>(istream& is, R&& r) -> decltype(is >> *begin(r)) {
  for (auto&& e : r) {
    is >> e;
  }
  return is;
}

template <class T1, class T2>
ostream& operator<<(ostream& os, const pair<T1, T2>& p) {
  return os << p.first << ' ' << p.second;
}

template <class... Ts>
ostream& operator<<(ostream& os, const tuple<Ts...>& t) {
  auto f = [&os](const auto&... xs) -> ostream& {
    [[maybe_unused]] auto sep = "";
    ((os << exchange(sep, " ") << xs), ...);
    return os;
  };
  return apply(f, t);
}

template <class R, enable_if_t<!is_convertible_v<R, string_view>>* = nullptr>
auto operator<<(ostream& os, R&& r) -> decltype(os << *begin(r)) {
  auto sep = "";
  for (auto&& e : r) {
    os << exchange(sep, " ") << e;
  }
  return os;
}

}  // namespace std

void scan(auto&&... xs) { (cin >> ... >> xs); }
void print(auto&&... xs) { cout << tie(xs...) << '\n'; }

inline auto rep(int l, int r) { return views::iota(min(l, r), r); }
inline auto rep(int n) { return rep(0, n); }
inline auto rep1(int l, int r) { return rep(l, r + 1); }
inline auto rep1(int n) { return rep(1, n + 1); }
inline auto per(int l, int r) { return rep(l, r) | views::reverse; }
inline auto per(int n) { return per(0, n); }
inline auto per1(int l, int r) { return per(l, r + 1); }
inline auto per1(int n) { return per(1, n + 1); }

inline auto len = ranges::ssize;

#endif  // __INCLUDE_LEVEL__