#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0;i < (n);i++)
int main(){
  int t;
  cin >> t;
  vector<vector<int>> ans(t);

  rep(i,t){
    int n;
    cin >> n;
    vector<int> p(n);
    map<int,int> mp;
    rep(j,n) cin >> p[j],mp[--p[j]] = j;
    rep(j,n){
      int cnt = mp[j];
      if(p[cnt] == cnt)continue;
      cnt--;
      int flag = 1;
      while(cnt >= j ){
        if(p[cnt] == cnt){
          flag = -1;break;
        }else swap(p[cnt],p[cnt+1]);
        ans[i].push_back(cnt+1);
        cnt--;
      }
      if(flag == -1){
        ans[i].clear();
        ans[i].push_back(-1);
        break;
      }
    }
  }

  rep(i,t){
    if(ans[i].size() == 1 && ans[i][0] == -1)cout << -1 << endl;
    else{
      cout << ans[i].size() << endl;
      rep(j,ans[i].size()){
        cout << ans[i][j] << " ";
      }
      cout << endl;
    }
  }
  return 0;
}