#include <bits/stdc++.h>
/*
5 2
1 100 100 100 100
101 101
*/
template<class _Tp = int>
_Tp read() {
  _Tp ret = 0;
  char ch = getchar(), sgn = 0;
  while (!isdigit(ch)) sgn |= ch == '-', ch = getchar();
  while (isdigit(ch)) ret = ret * 10 + ch - '0', ch = getchar();
  return sgn ? -ret : ret;
}

const int kMaxN = 3e5 + 5;
int n, m, L;
long long dis;
int a[kMaxN], b[kMaxN];
std::vector<int> ans;

void clear() {

}
bool solve() {
  ans.clear();
  std::multiset<int> S;
  for (int i = m + 1; i <= n; i++)
    S.insert(a[i]);
  int x = m, y = 0;
  while (x && a[x] == a[m]) x--;
  x = m - x;
  // while (y <= n && a[y] == a[m]) y++;
  // y = y - m - 1;
  // DON'T DO THAT
  int r = L - dis;
  while (r > 0) {
    // fprintf(stderr, "ROUND\n");
    if (S.empty())
      return false;
    int c = *S.begin();
    if (c == b[m])
      return false;
    if (c == a[m]) {
    // qiong tu mo lu le
    // cong y li xi sheng x ge am
      // printf("? x%d y%d r%d r+dis%d \n", x, y, r, r + dis);
      y = S.count(a[m]);
      if (y < r + dis || x > y)
        return false;
      else {
        for (int i = 1; i <= x; i++)
          ans.push_back(a[m]);
        for (int i = m - x + 1; i <= m; i++)
          a[i]++;
        for (int i = 1; i <= x; i++)
          S.erase(S.begin());
        // update x
        x = m - x;
        while (x && a[x] == a[m])
          x--;
        x = m - x;
      }
      continue;
    }
    ans.push_back(c);
    S.erase(S.begin());
    S.insert(c + 1);
    S.erase(S.begin());
    r--;
  }
  for (int i = 1; i <= m; i++)
    while (a[i] < b[i])
      ans.push_back(a[i]), a[i]++;
  // print_ans();
  // fprintf(stderr, "HELLO : L%d ans.size() %d\n", L, ans.size());
  // for (auto i : ans)
  //   fprintf(stderr, "ans %d \n", i);
  assert(ans.size() == n - m);
  return true;
}


int main() {
  int T = read();
  while (T--) {
    n = read(), m = read();
    L = n - m;
    for (int i = 1; i <= n; i++)
      a[i] = read();
    for (int i = 1; i <= m; i++)
      b[i] = read();
    std::sort(a + 1, a + n + 1, std::greater<int>());
    std::sort(b + 1, b + m + 1, std::greater<int>());
    dis = 0;
    for (int i = 1; i <= m; i++) {
      if (a[i] > b[i]) {
        puts("-1");
        goto end_of_loop;
      }
      dis += b[i] - a[i];
    }
    // fprintf(stderr, "dis %d?\n", dis);
    if (dis > L) {
      puts("-1");
      goto end_of_loop;
    } 
    if (solve()) {
      printf("%d\n", L);
      for (auto i : ans)
        printf("%d ", i);
      puts("");
    } else 
      puts("-1");
    end_of_loop:
      clear();
  }
}

/*
7
5 3
1 2 2 3 3
2 3 4
4 2
1 2 2 4
2 4
5 2
2 3 3 4 4
5 5
6 1
1 1 1 1 1 1
4
4 2
1 1 1 2
2 2
4 1
1 1 1 1
2
5 1
1 1 1 1 2
3
*/