#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,avx,avx2,fma,tune=native")

#define ll long long
#define int ll
#define ull unsigned ll
#define ld long double
#define rep(a) rep1(i,a)
#define rep1(i,a) rep2(i,0,a)
#define rep2(i,b,a) for(int i=(b); i<((int)(a)); i++)
#define rep3(i,b,a) for(int i=(b); i>=((int)(a)); i--)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define pb push_back
//#define inf 1010000000
#define inf 4000000000000000000
#define eps 1e-9
#define sz(a) ((int)a.size())
#define pow2(x) (1ll<<(x))
#define ceiling(a,b) (((a)+(b)-1)/(b))
#define print0(a) cout << (a) << ' '
#define ykh mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#ifdef i_am_noob
#define bug(...) cerr << "#" << __LINE__ << ' ' << #__VA_ARGS__ << "- ", _do(__VA_ARGS__)
template<typename T> void _do(vector<T> x){for(auto i: x) cerr << i << ' ';cerr << "\n";}
template<typename T> void _do(set<T> x){for(auto i: x) cerr << i << ' ';cerr << "\n";}
template<typename T> void _do(T && x) {cerr << x << endl;}
template<typename T, typename ...S> void _do(T && x, S&&...y) {cerr << x << ", "; _do(y...);}
#else
#define bug(...) 826
#endif
template<typename T> void print(T && x) {cout << x << "\n";}
template<typename T, typename... S> void print(T && x, S&&... y) {cout << x << ' ';print(y...);}

const int Mod=1000000007,Mod2=998244353;
const int MOD=Mod2;
const int maxn=505;

//i_am_noob
#define wiwihorz  
int n,a[maxn];
vector<int> res;

void op(int x){
    if((x+sz(res))&1){
        bug(x,sz(res));
    }
    if(sz(res)==60604) bug(x);
    assert((x+1+sz(res))&1);
    res.pb(x+1);
    swap(a[x],a[x+1]);
}

void report(){
    print(sz(res));
    for(auto i: res) print0(i);
    cout << "\n";
}

void orzck(){
    res.clear();
    cin >> n;
    rep(n) cin >> a[i];
    rep(n) a[i]--;
    if(n<=3){
        while(!is_sorted(a,a+n)){
            if(sz(res)&1) op(1);
            else op(0);
        }
        report();
        return;
    }
    rep3(i,n-1,4){
        int pos;
        rep1(j,n) if(a[j]==i) pos=j;
        if((pos+sz(res))&1){
            if(sz(res)&1) op(pos==2?3:1);
            else op(pos==1?2:0);
        }
        rep2(j,pos,i) op(j);
    }
    bug(sz(res));
    rep(n) bug(a[i]);
    int pos;
    if(sz(res)&1) op(1);
    rep(4) if(a[i]==3) pos=i;
    if((pos+1+sz(res))&1){
        rep2(i,pos,3) op(i);
    }
    else if(pos<3){
        op(2);
        rep2(i,pos,3) op(i);
    }
    rep(n) bug(a[i]);
    while(!is_sorted(a,a+n)){
        if(sz(res)&1) op(1);
        else op(0);
    }
    assert(is_sorted(a,a+n));
    report();
}

signed main(){
    ios_base::sync_with_stdio(0),cin.tie(0);
    #ifdef i_am_noob
    freopen("input1.txt","r",stdin);
    freopen("output1.txt","w",stdout);
    freopen("output2.txt","w",stderr);
    #endif
    cout << fixed << setprecision(15);
    int t;
    #ifdef wiwihorz
    cin >> t;
    #else
    t=1;
    #endif
    while(t--) orzck();
    return 0;
}
#pragma GCC optimize(2)
//#include <bits/stdc++.h>
#include <iostream>
#include <set>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
#include <vector>
#include <utility>
#include <map>
#define rush()      int T; while(cin>>T) while(T--)
#define ms(a,b)     memset(a,b,sizeof a)
#define lowbit(x)   ((x)&(-x))
#define inf         0x7f7f7f7fll
#define eps         1e-11
#define sd(a)       scanf("%d",&a)
#define sll(a)      scanf("%lld",&a)
#define sll2(a,b)   scanf("%lld%lld",&a,&b)
#define sll3(a,b,c) scanf("%lld%lld%lld",&a,&b,&c)
#define sdd(a,b)    scanf("%d%d",&a,&b)
#define sddd(a,b,c) scanf("%d%d%d",&a,&b,&c)
#define sf(a)       scanf("%lf",&a)
//#define sc(a)       scanf("%c\n",&a)
#define ss(a)       scanf("%s",a)
#define pd(a)       printf("%d\n",a)
#define pdd(a,b)    printf("%d %d\n",a,b)
#define pddd(a,b,c) printf("%d %d %d\n",a,b,c)
#define pll(a)      printf("%lld\n",a)
#define pf(a)       printf("%.1lf\n",a)
#define pc(a)       printf("%c",a)
#define ps(a)       printf("%s\n",a)
#define rep(i,a,b)  for(int i=(a);i<=(b);i++)
#define forn(i,a,b,x)  for(int i=(a);i<=(b);i+=(x))
#define per(i,a,b)  for(int i=(b);i>=(a);i--)
#define pb(a)       push_back(a)
#define mp(a,b)     make_pair(a,b)
#define debug(a)    cout<<#a<<" : "<<a<<" "<<" ; "
#define dbg(a)      cout<<#a<<" : "<<a<<endl
#define show(a,b)   cout<<a<<" :\t"<<b<<"\t*"<<endl
#define IOS         ios::sync_with_stdio(0); cin.tie(0)
#define PAUSE       system("pause")
#define all(x)      x.begin(),x.end()
//#define print(a)    cout<<a<<endl;continue;
#define fr          first
#define sc          second
#define ceils(a,b)  ((a-1ll+b)/(b))
#define floors(a,b) floor(double(a)/double(b))
using namespace std;
//inline void swap(int &x,int &y){x^=y^=x^=y;}
typedef long long ll;
//using ui=unsigned int;
typedef unsigned long long ull;
typedef pair<int,int> pii;
const double pi=acos(-1.0);
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};
const int limit=5e5;

int read()
{
	int s=0;
	char c=getchar(),lc='+';
	while (c<'0'||'9'<c) lc=c,c=getchar();
	while ('0'<=c&&c<='9') s=s*10+c-'0',c=getchar();
	return lc=='-'?-s:s;
}

void write(int x)
{
	if (x<0) putchar('-'),x=-x;
	if (x<10) putchar(x+'0');
	else write(x/10),putchar(x%10+'0');
}

void print(int x,char c='\n')
{
	write(x);
	putchar(c);
}

ll mod=2147483648;
const int N=3e5+5;
 
    int n, m, _;
    int i, j, k;
    int a[N];
    int pos[N];
    vector<int> ans;

signed main()
{
    //IOS;
    rush(){
        sd(n);
        rep(i, 1, n) sd(a[i]), pos[a[i]] = i;
        int opt = 1;
        rep(i, 1, n){
            if(i == pos[i]) continue;
            if((pos[i] - 1) % 2 != opt){
                if(pos[i] - 2 >= i){
                    ans.pb(pos[i] - 2);
                    int x = pos[i] - 2, y = pos[i] - 1;
                    swap(pos[a[x]], pos[a[y]]);
                    swap(a[x], a[y]);
                    opt ^= 1;
                }
                else if(pos[i] == i + 1){
                    ans.pb(i - 1);
                    ans.pb(i);
                    ans.pb(i - 1);
                    ans.pb(i);
                    ans.pb(i - 1);
                    //ans.pb(i);
                    opt ^= 1;
                    int x = pos[i], y = pos[i] - 1;
                    swap(pos[a[x]], pos[a[y]]);
                    swap(a[x], a[y]);
                    continue;
                }
            }
            for(int j = pos[i] - 1; j >= i; j--){
                ans.pb(j);
                int x = j, y = j + 1;
                swap(pos[a[x]], pos[a[y]]);
                swap(a[x], a[y]);
                opt ^= 1;
            }
        }
        pd(ans.size());
        for(auto it : ans) printf("%d ", it);
        puts("");
        ans.clear();
    }
    //PAUSE;
    return 0;
}
