T = int(input())


import sys
sys.setrecursionlimit(10 ** 8)

def calc(p,ans):
    N = len(p)
    if N == 1:return True
    while 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]

    
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)