#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//const long nPrime = 1000000007;
//const long nPrime = 998244353;
typedef long long ll;
void Swap(long i, vector<long> &viNum, vector<long> &viAns){
    viAns.push_back(i+1);
    swap(viNum[i], viNum[i+1]);
}
int main() {
    long t;
    cin >> t;
    while(t--){
        long n;
        cin >> n;
        vector<long> viNum(n), viInv(n);
        for(long i = 0; i < n; i++){
            cin >> viNum[i];
        }
        long nSum = 0;
        for(long i = 0; i < n; i++){
            if(viNum[i] == i+1 && nSum != i*(i+1)/2){
                cout << -1 << endl;
                break;
            }
            nSum += viNum[i];
        }
        
        vector<long> viAns;
        viAns.resize(n*n);
        for(long i = 0; i < n; i++){
            vector<long> viSum(n,0);
            long nTmp = 0;
            for(long j = 0; j < n; j++){
                nTmp += viNum[j];
                viSum[j] = nTmp;
            }
            long k = i;
            while(viNum[k] != i+1){
                k++;
            }
            while(k > i){
                long m = k-1;
                while(viNum[m] == m+2 && viSum[m]+i+1 != (m+2)*(m+3)/2){
                    m--;
                }
                for(; m < k-1; m++){
                    Swap(m,viNum,viAns);
                }
                Swap(k-1,viNum,viAns);
            }
        }
        cout << viAns.size() << endl;
        for(long i = 0; i < viAns.size(); i++){
            cout << viAns[i] << " ";
        }
        cout << endl;
    }
    return 0;
}