T = int(input())


import sys
sys.setrecursionlimit(10 ** 8)

def calc(p,ans):
    N = len(p)
    if N == 1:return True
    for i in range(N):
        if p[i] == N:
            index = i
            break
    if index == N-1:
        return calc(p[:-1],ans)
    r = index + 1
    while r < N:
        if p[r] == r + 1:
            return False
        if p[r] == r:
            r += 1
        else:
            break
    if r == N:
        if p[index+1] == index+1:
            r -= 1
        else:
            return False
    for k in range(r-1,index-1,-1):
        ans.append(k+1)
        p[k],p[k+1] = p[k+1],p[k]
    return calc(p,ans)

    
for _ in range(T):
    N = int(input())
    p = list(map(int,input().split()))
    ans = []
    if calc(p,ans):
        print(len(ans))
        print(*ans)
    else:
        print(-1)