def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    return (g1[n] * g2[r] % mod) * g2[n-r] % mod

mod = 998244353
N = 2*10**5
g1 = [1]*(N+1)
g2 = [1]*(N+1)
inverse = [1]*(N+1)

for i in range( 2, N + 1 ):
    g1[i]=( ( g1[i-1] * i ) % mod )
    inverse[i]=( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2[i]=( (g2[i-1] * inverse[i]) % mod )
inverse[0]=0


import sys,random,bisect
from collections import deque,defaultdict
from heapq import heapify,heappop,heappush
from itertools import permutations
from math import e, log,gcd

input = lambda :sys.stdin.readline()
mi = lambda :map(int,input().split())
li = lambda :list(mi())

for _ in range(int(input())):
    N = int(input())
    P = li()
    res = []
    flag = True
    for i in range(N):
        pos = P.index(i+1)
        for j in range(i,pos):
            if P[j]==j+1:
                flag = False
                break
        if not flag:
            break

        while pos!=i:
            s = -1
            for j in range(i,pos)[::-1]:
                if P[j]!=j+2:
                    s = j
                    break
            if s==-1:
                for j in range(i,pos)[::-1]:
                    res.append(j+1)
                    P[j],P[j+1] = P[j+1],P[j]
                    #print(P)
                pos = i
            else:
                for j in range(s,pos):
                    res.append(j+1)
                    P[j],P[j+1] = P[j+1],P[j]
                    #print(P)
                res.append(pos)
                P[pos-1],P[pos] = P[pos],P[pos-1]
                #print(P)
                pos = pos-1
    
    #print(P)
    
    if flag:
        print(len(res))
        print(*res)
    else:
        print(-1)