#include <bits/stdc++.h>

using namespace std;

const int N = 2e5+5;

int n;
int g[N], v[N<<1], nxt[N<<1], tot;
int fa[N], son[N];
int dfn[N], sec;

inline void add(int x, int y) {
	v[++tot] = y, nxt[tot] = g[x], g[x] = tot;
}

void dfs0(int x, int f, int dis, int &t, int &mn) {
	fa[x] = f;
	if (dis > mn) t = x, mn = dis;
	for (int i = g[x]; i; i = nxt[i]) {
		int y = v[i];
		if (y == fa[x]) continue;
		dfs0(y, x, dis + 1, t, mn);
	}
}

void dfs1(int x) {
	dfn[x] = ++sec;
	for (int i = g[x]; i; i = nxt[i]) {
		int y = v[i];
		if (y == fa[x] || y == son[x]) continue;
		dfs1(y);
		sec++;
	}
	if (son[x]) dfs1(son[x]);
}

int main()
{
	scanf("%d", &n);
	for (int i = 1; i < n; i++) {
		int x, y; scanf("%d%d", &x, &y);
		add(x, y), add(y, x);
	}
	int s, t, mn = -1;
	dfs0(1, 0, 0, s, mn);
	mn = -1;
	dfs0(s, 0, 0, t, mn);
	//直径 s -> t 
	for (int i = t; i != s; i = fa[i]) son[fa[i]] = i;
	dfs1(s);
	for (int i = 1; i <= n; i++) printf("%d ", dfn[i]);
	return 0;
}
#include <bits/stdc++.h>
using namespace std;
//using namespace atcoder;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin);i<(end);i++)
#define REP(i, n) FOR(i,0,n)
#define IFOR(i, begin, end) for(int i=(end)-1;i>=(begin);i--)
#define IREP(i, n) IFOR(i,0,n)
#define Sort(v) sort(v.begin(), v.end())
#define Reverse(v) reverse(v.begin(), v.end())
#define all(v) v.begin(),v.end()
#define SZ(v) ((int)v.size())
#define Lower_bound(v, x) distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) distance(v.begin(), upper_bound(v.begin(), v.end(), x))
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define bit(n) (1LL<<(n))
#define debug(x) cout << #x << "=" << x << endl;
#define vdebug(v) { cout << #v << "=" << endl; REP(i_debug, v.size()){ cout << v[i_debug] << ","; } cout << endl; }
#define mdebug(m) { cout << #m << "=" << endl; REP(i_debug, m.size()){ REP(j_debug, m[i_debug].size()){ cout << m[i_debug][j_debug] << ","; } cout << endl;} }
#define pb push_back
#define fi first
#define se second
#define int long long
#define INF 1000000000000000000
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for (auto &x : v) is >> x; return is; }
template<typename T> ostream &operator<<(ostream &os, vector<T> &v){ for(int i = 0; i < v.size(); i++) { cout << v[i]; if(i != v.size() - 1) cout << endl; }; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, pair<T1, T2> p){ cout << '(' << p.first << ',' << p.second << ')'; return os; }
template<typename T> void Out(T x) { cout << x << endl; }
template<typename T1, typename T2> void chOut(bool f, T1 y, T2 n) { if(f) Out(y); else Out(n); }

using vec = vector<int>;
using mat = vector<vec>;
using Pii = pair<int, int>;
using v_bool = vector<bool>;
using v_Pii = vector<Pii>;

//int dx[4] = {1,0,-1,0};
//int dy[4] = {0,1,0,-1};
//char d[4] = {'D','R','U','L'};

const int mod = 1000000007;
//const int mod = 998244353;



signed main(){

    int T; cin >> T;
    REP(_, T){
        int N; cin >> N;
        vec p(N); cin >> p;
        REP(i, N) p[i]--;

        vec ans;
        if(N == 2){
            if(p[0] == 1) ans.pb(0);
        }else{
            IFOR(t, 3, N){
                int now = -1;
                REP(i, N) if(p[i] == t) now = i;
                if(now == t) continue;
                if(now % 2 != SZ(ans) % 2){
                    if(now == 0){
                        ans.pb(1);
                        swap(p[1], p[2]);
                    }else{
                        ans.pb(now - 1);
                        swap(p[now - 1], p[now]);
                        now--;
                        ans.pb(now + 1);
                        swap(p[now + 1], p[now + 2]);
                    }
                }
                while(now != t){
                    ans.pb(now);
                    swap(p[now], p[now + 1]);
                    now++;
                }
            }
            while(p[0] != 0 || p[1] != 1 || p[2] != 2){
                if(SZ(ans) % 2 == 0){
                    ans.pb(0);
                    swap(p[0], p[1]);
                }else{
                    ans.pb(1);
                    swap(p[1], p[2]);
                }
            }
        }
        Out(SZ(ans));
        for(int x: ans) cout << x + 1 << " ";
        cout << endl;
    }

    return 0;
}
