#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;   }   