#include <algorithm>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int t;
  cin >> t;
  while (t--) {
    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];
    }
    bool bad = false;
    ll need = 0;
    for (int i = 0; i < m; ++i) {
      if (b[i] < a[n - m + i]) {
        bad = true;
        break;
      } else {
        need += b[i] - a[n - m + i];
      }
    }
    if (bad || need > n - m) {
      cout << "-1\n";
      continue;
    }
    vector<int> ans;
    int bound = b[0];
    multiset<int> lf, rg;
    for (int i = 0; i < n; ++i) {
      if (i < n - m) {
        lf.insert(a[i]);
      } else {
        rg.insert(a[i]);
      }
    }
    multiset<int> bs;
    for (int i = 0; i < m; ++i) {
      bs.insert(b[i]);
    }
    int need_musor = n - m - need;
    for (int it = 0; it < n - m; ++it) {
      int after_op = (*lf.begin()) + 1;
      if (lf.size() >= 2) {
        after_op = min(after_op, *next(lf.begin()));
      }
      int min_r = bound;
      if (!rg.empty()) {
        min_r = min(min_r, *rg.begin());
      }
      if (need_musor > 0 && after_op <= min_r) {
        --need_musor;
        auto x = *lf.begin();
        ans.push_back(x);
        lf.erase(lf.begin());
        lf.insert(x + 1);
      } else {
        if (need == 0) {
          bad = true;
          break;
        }
        --need;
        assert(!rg.empty());
        while ((*rg.begin()) == (*bs.begin())) {
          rg.erase(rg.begin());
          bs.erase(bs.begin());
          assert(!rg.empty());
        }
        auto x = *rg.begin();
        ans.push_back(x);
        rg.erase(rg.begin());
        rg.insert(x + 1);
      }
      min_r = bound;
      if (!rg.empty()) {
        min_r = min(min_r, *rg.begin());
      }
      if ((*lf.begin()) > min_r) {
        bad = true;
        break;
      }
      lf.erase(lf.begin());
    }

    if (bad) {
      cout << "-1\n";
      continue;
    }

    cout << ans.size() << '\n';
    for (auto x : ans) {
      cout << x << ' ';
    }
    cout << '\n';
  }
}