Problem: You are given an array a consisting of n integers.

In one move, you can choose some index i (1 ≤ i ≤ n - 2) and shift the segment [a_i, a_{i + 1}, a_{i + 2}] cyclically to the right (i.e. replace the segment [a_i, a_{i + 1}, a_{i + 2}] with [a_{i + 2}, a_i, a_{i + 1}]). 

Your task is to sort the initial array by no more than n^2 such operations or say that it is impossible to do that.

You have to answer t independent test cases.

Input

The first line of the input contains one integer t (1 ≤ t ≤ 100) — the number of test cases. Then t test cases follow.

The first line of the test case contains one integer n (3 ≤ n ≤ 500) — the length of a. The second line of the test case contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 500), where a_i is the i-th element a.

It is guaranteed that the sum of n does not exceed 500.

Output

For each test case, print the answer: -1 on the only line if it is impossible to sort the given array using operations described in the problem statement, or the number of operations ans on the first line and ans integers idx_1, idx_2, ..., idx_{ans} (1 ≤ idx_i ≤ n - 2), where idx_i is the index of left border of the segment for the i-th operation. You should print indices in order of performing operations.

Example

Input


5
5
1 2 3 4 5
5
5 4 3 2 1
8
8 4 5 2 3 6 7 3
7
5 2 1 6 4 7 3
6
1 2 3 3 6 4


Output


0

6
3 1 3 2 2 3 
13
2 1 1 6 4 2 4 3 3 4 4 6 6 
-1
4
3 3 4 4 

Solution (in PYTHON):

Solution:

# Author : raj1307 - Raj Singh
# Date   : 28.06.2020

from __future__ import division, print_function

import os,sys
from io import BytesIO, IOBase

if sys.version_info[0] < 3:
    from __builtin__ import xrange as range
    from future_builtins import ascii, filter, hex, map, oct, zip


def ii():  return int(input())
def si():  return input()
def mi():  return map(int,input().strip().split(" "))
def msi(): return map(str,input().strip().split(" "))
def li():  return list(mi())

def dmain():
    sys.setrecursionlimit(100000000)
    threading.stack_size(10240000)
    thread = threading.Thread(target=main)
    thread.start()
    
#from collections import deque, Counter, OrderedDict,defaultdict
#from heapq import nsmallest, nlargest, heapify,heappop ,heappush, heapreplace
#from math import log,sqrt,factorial,pi
#from bisect import bisect,bisect_left,bisect_right,insort,insort_left,insort_right
#from decimal import *,threading
#from itertools import permutations
#Copy 2D list  m = [x[:] for x in mark] .. Avoid Using Deepcopy

abc='abcdefghijklmnopqrstuvwxyz'
abd={'a': 0, 'b': 1, 'c': 2, 'd': 3, 'e': 4, 'f': 5, 'g': 6, 'h': 7, 'i': 8, 'j': 9, 'k': 10, 'l': 11, 'm': 12, 'n': 13, 'o': 14, 'p': 15, 'q': 16, 'r': 17, 's': 18, 't': 19, 'u': 20, 'v': 21, 'w': 22, 'x': 23, 'y': 24, 'z': 25}
mod=1000000007
#mod=998244353
inf = float("inf")
vow=['a','e','i','o','u']
dx,dy=[-1,1,0,0],[0,0,1,-1]
def getKey(item): return item[0] 
def sort2(l):return sorted(l, key=getKey)
def d2(n,m,num):return [[num for x in range(m)] for y in range(n)]
def isPowerOfTwo (x): return (x and (not(x & (x - 1))) )
def decimalToBinary(n): return bin(n).replace("0b","")
def ntl(n):return [int(i) for i in str(n)]
def ncr(n,r): return factorial(n)//(factorial(r)*factorial(n-r))

def ceil(x,y):
    if x%y==0:
        return x//y
    else:
        return x//y+1

def powerMod(x,y,p):
    res = 1
    x %= p
    while y > 0:
        if y&1:
            res = (res*x)%p
        y = y>>1
        x = (x*x)%p
    return res

def gcd(x, y):
    while y:
        x, y = y, x % y
    return x
    
def isPrime(n) : # Check Prime Number or not 
    if (n <= 1) : return False
    if (n <= 3) : return True
    if (n % 2 == 0 or n % 3 == 0) : return False
    i = 5
    while(i * i <= n) : 
        if (n % i == 0 or n % (i + 2) == 0) : 
            return False
        i = i + 6
    return True



def read():
    sys.stdin = open('input.txt', 'r')  
    sys.stdout = open('output.txt', 'w') 






def main():
    

    
    for _ in range(ii()):

        
    
        n=ii()
        a=li()
        ans=[]
        cur=0
        f=1
        pos=0
        l=[]
        for i in range(n):
            l.append(a[i])
        l.sort()
      

        
        while pos!=n-1:  # for every mum in thr array
            
            if f==0:   # if fslse directly break out of the loop
                break
         
            cur=l[pos]
            #print(a,ans)

            for i in range(n):
                
                if a[i]==cur and pos<=i:

                    #print(i,pos,"i")
                    if i==pos: # if the eleemnt is already in th req pos
                        break

                    j=i

                    #print(j,pos)


                    if pos==n-2: #  need to check if we have reached the second last ele 


                        if a[pos]<=a[pos+1]:
                            break

                        X=a[pos-1]
                        Y=a[pos]
                        Z=a[pos+1]

                        a[pos-1]=Z
                        a[pos]=X
                        a[pos+1]=Y
                        ans.append(pos-1)
                        if a[pos-1] <= a[pos] and a[pos] <= a[pos+1]:
                            break

                        flag=0
                        #print(pos,'k')
                        for i in range(pos-1,0,-1):


                            X=a[i-1]
                            Y=a[i]
                            Z=a[i+1]

                            a[i-1]=Z
                            a[i]=X
                            a[i+1]=Y
                            ans.append(i-1)

                            if a[i-1] <= a[i] and a[i] <= a[i+1]:
                                flag=1
                                break






                            # if a[i]==a[i-1]:
                            #     #print(i,'i')
                            #     ans.append(i)
                            #     #
                            #     #flag=1
                            #     break
                            # else:
                            #     ans.append(i)

                        if flag==0: 
                            f=0


                        break






                        # 2 2 3 5 4  
                        # 2 2 4 3 5
                        # 2 3 2 4 5
                        # 2 2 3 4 5

                        # 2 3 3 5 4
                        # 2 3 4 3 5










                    deb=0

                    while True:

                        # print(j,'p',i)
                        # print(a)

                        # if deb==10:
                        #     break


                        if j-pos<=2:
                            # print(a)
                            # print(pos,pos+1,pos+2,cur,pos)
                            X=a[pos]
                            Y=a[pos+1]
                            Z=a[pos+2]
                            if X==cur:
                                break
                            ans.append(pos)

                            if Y==cur:
                                #ans.append(pos)
                                a[pos]=Z
                                a[pos+1]=X
                                a[pos+2]=Y

                            elif Z==cur: 
                                #ans.append(pos)
                                a[pos]=Z
                                a[pos+1]=X
                                a[pos+2]=Y

                        else:
                            ans.append(j-2)


                            X=a[j-2]
                            Y=a[j-1]
                            Z=a[j]  

                            #print(X,Y,Z,a,j)

                            a[j-2]=Z
                            a[j-1]=X
                            a[j]=Y
                            j-=2

                        #deb+=1

     
            pos+=1


        if f==0:
            print(-1)
        else:
            print(len(ans))
            for i in range(len(ans)):
                print(ans[i]+1,end=' ')
            print()













       















# region fastio 
# template taken from https://github.com/cheran-senthil/PyRival/blob/master/templates/template.py

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


def print(*args, **kwargs):
    """Prints the values to a stream, or to sys.stdout by default."""
    sep, file = kwargs.pop("sep", " "), kwargs.pop("file", sys.stdout)
    at_start = True
    for x in args:
        if not at_start:
            file.write(sep)
        file.write(str(x))
        at_start = False
    file.write(kwargs.pop("end", "\n"))
    if kwargs.pop("flush", False):
        file.flush()


if sys.version_info[0] < 3:
    sys.stdin, sys.stdout = FastIO(sys.stdin), FastIO(sys.stdout)
else:
    sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)

input = lambda: sys.stdin.readline().rstrip("\r\n")

# endregion


if __name__ == "__main__":
    #read()
    main()
    #dmain()

# Comment Read()