def yesno(p):
    for idx, (_, i) in enumerate(p):
        if idx == i and sum(j < i for _, j in p[:idx]) != i:
            return False
    return True


def swap(p, i, ops, comp):
    if p[i][1] == i or p[i+1][1] == i+1:
        return
    if comp(p[i]) > comp(p[i+1]):
        p[i], p[i+1] = p[i+1], p[i]
        ops.append(i+1)


def sort(p, ops, comp):
    for _ in p:
        for i in range(len(p)-1):
            swap(p, i, ops, comp)


def solve():
    n = int(input())
    p = [(i-1 < idx, i-1) for idx, i in enumerate(map(int, input().split()))]

    if not yesno(p):
        print(-1)
        return

    ops = []
    sort(p, ops, lambda x: x)
    sort(p, ops, lambda x: x[1])
    print(len(ops))
    print(" ".join(map(str, ops)))


if __name__ == "__main__":
    t = int(input())
    for _ in range(t):
        solve()