mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    for _ in range(int(input())):
        N = int(input())
        P = [0] + list(map(int, input().split()))

        ans = []
        ok = 1
        for p in range(1, N + 1):
            for i in range(1, N+1):
                if P[i] == p:
                    ii = i
                    break
            if ii == p:
                continue
            iii = ii
            for i in range(p, ii):
                if P[i] != i + 1:
                    iii = i
                    break
            for i in range(iii + 1, ii - 1):
                ans.append(i)
                if P[i] == i or P[i+1] == i+1:
                    ok = 0
                P[i], P[i + 1] = P[i + 1], P[i]
            for i in range(ii - 1, p - 1, -1):
                ans.append(i)
                if P[i] == i or P[i+1] == i+1:
                    ok = 0
                P[i], P[i + 1] = P[i + 1], P[i]
        if ok:
            print(len(ans))
            print(*ans)
            assert len(ans) <= N ** 2
        else:
            print(-1)


if __name__ == '__main__':
    main()