def solve():
    n = int(input())
    P = list(map(int, input().split()))
    ans = []
    for i in range(1, n):
        for j in range(i - 1, -1, -1):
            if P[j + 1] < P[j]:
                if P[j + 1] == j + 2 or P[j] == j + 1:
                    print(-1)
                    return
                ans.append(j + 1)
                P[j], P[j + 1] = P[j + 1], P[j]
                
    print(len(ans))
    print(*ans)
    
    
for _ in range(int(input())):
    solve()