#include <bits/stdc++.h>
using namespace std;
const int N = 4e6 + 10;
int n, m;
int a[N];
int find(int x) {
  for (int i = 1; i <= n; i++) {
    if (a[i] == x) return i;
  }
}
vector<int> v;
signed main() {
  int x, y, z, T;
  cin >> T;
  while (T--) {
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
    bool f = 0;
    for (int i = 1; i <= n; i += 2)
      if (a[i] % 2 == 0) f = 1;
    if (f) {
      puts("-1");
      continue;
    }
    v.clear();
    for (int i = n; i >= 1; i -= 2) {
      if (i == 1) continue;
      int l = find(i), r = find(i - 1);
      if (l == i && r == i - 1) continue;
      if (l == 1 && r == 2) {
        v.push_back(i);
        reverse(a + 1, a + 1 + i);
        continue;
      }
      v.push_back(l);
      reverse(a + 1, a + 1 + l);
      l = 1, r = find(i - 1);
      if (l == 1 && r == 2) {
        v.push_back(i);
        reverse(a + 1, a + 1 + i);
        continue;
      }
      v.push_back(r - 1);
      reverse(a + 1, a + 1 + r - 1);
      v.push_back(r + 1);
      reverse(a + 1, a + 1 + r + 1);
      v.push_back(3);
      reverse(a + 1, a + 1 + 3);
      v.push_back(i);
      reverse(a + 1, a + 1 + i);
    }
    cout << v.size() << endl;
    for (int i : v) cout << i << " ";
    cout << endl;
  }
  return 0;
}
