#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < n; i++)
#define rep2(i, x, n) for (int i = x; i <= n; i++)
#define rep3(i, x, n) for (int i = x; i >= n; i--)
#define each(e, v) for (auto &e : v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;

template <typename T>
bool chmax(T &x, const T &y) {
    return (x < y) ? (x = y, true) : false;
}

template <typename T>
bool chmin(T &x, const T &y) {
    return (x > y) ? (x = y, true) : false;
}

template <typename T>
int flg(T x, int i) {
    return (x >> i) & 1;
}

template <typename T>
void print(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << (i == n - 1 ? '\n' : ' ');
    if (v.empty()) cout << '\n';
}

template <typename T>
void printn(const vector<T> &v, T x = 0) {
    int n = v.size();
    for (int i = 0; i < n; i++) cout << v[i] + x << '\n';
}

template <typename T>
int lb(const vector<T> &v, T x) {
    return lower_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
int ub(const vector<T> &v, T x) {
    return upper_bound(begin(v), end(v), x) - begin(v);
}

template <typename T>
void rearrange(vector<T> &v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <typename T>
vector<int> id_sort(const vector<T> &v, bool greater = false) {
    int n = v.size();
    vector<int> ret(n);
    iota(begin(ret), end(ret), 0);
    sort(begin(ret), end(ret), [&](int i, int j) { return greater ? v[i] > v[j] : v[i] < v[j]; });
    return ret;
}

template <typename S, typename T>
pair<S, T> operator+(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first + q.first, p.second + q.second);
}

template <typename S, typename T>
pair<S, T> operator-(const pair<S, T> &p, const pair<S, T> &q) {
    return make_pair(p.first - q.first, p.second - q.second);
}

template <typename S, typename T>
istream &operator>>(istream &is, pair<S, T> &p) {
    S a;
    T b;
    is >> a >> b;
    p = make_pair(a, b);
    return is;
}

template <typename S, typename T>
ostream &operator<<(ostream &os, const pair<S, T> &p) {
    return os << p.first << ' ' << p.second;
}

struct io_setup {
    io_setup() {
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

const int inf = (1 << 30) - 1;
const ll INF = (1LL << 60) - 1;
const int MOD = 1000000007;
// const int MOD = 998244353;

vector<int> ans;

bool solve(vector<int> p, int l) {
    int n = sz(p);
    int mi = *min_element(all(p)), ma = *max_element(all(p));
    if (ma - mi != n - 1 || mi != l) return false;
    each(e, p) e -= l;

    rep(i, n) {
        int ptr = -1;
        rep2(j, i, n - 1) {
            if (p[j] == i) ptr = j;
        }

        for (int k = ptr - 1; k >= i;) {
            if (p[k] != k + 1) {
                k--;
                continue;
            }
            int j = 0;
            while (k - j >= i && p[k - j] == k - j + 1) j++;

            if (k - j >= i) {
                rep2(x, k - j, k - 1) {
                    ans.eb(l + x);
                    swap(p[x], p[x + 1]);
                }
            }
            k -= j + 1;
        }

        rep3(x, ptr - 1, i) {
            // cout << l + x << ' ';
            ans.eb(l + x);
            swap(p[x], p[x + 1]);
        }
        // print(p);
    }

    return true;
}

void simulate(vector<int> p, vector<int> ans) {
    print(p, 1);
    each(e, ans) {
        swap(p[e], p[e + 1]);
        print(p, 1);
    }
}

int main() {
    int T;
    cin >> T;

    while (T--) {
        int N;
        cin >> N;
        ans.clear();

        vector<int> p(N);
        rep(i, N) {
            cin >> p[i];
            p[i]--;
        }
        bool flag = true;

        for (int i = 0; i < N;) {
            if (p[i] == i) {
                i++;
                continue;
            }
            int j = 0;
            while (i + j < N && p[i + j] != i + j) j++;
            if (!solve(vector<int>(begin(p) + i, begin(p) + i + j), i)) {
                flag = false;
                break;
            }
            // cout << i << ' ' << j << '\n';
            i += j;
        }

        if (!flag) {
            cout << "-1\n";
        } else {
            cout << sz(ans) << '\n';
            print(ans, 1);
            // simulate(p, ans);
        }
    }
}