/*
 * Author: Md. Mahfuzur Rahman
 * Purpose: Competitive Programming
 */

#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <list>
#include <deque>
#include <array>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <queue>
#include <stack>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <utility>
#include <tuple>
#include <limits>
#include <functional>
#include <chrono>
#include <random>
#include <bitset>
#include <iomanip>
using namespace std;

#define ll long long
 #define pb push_back
 #define endl '\n'
 #define nl cout << endl
 #define ff first
 #define ss second
 #define all(v) v.begin(), v.end()
 #define rall(v) v.rbegin(), v.rend()
 #define srt(v) sort(v.begin(),v.end())
 #define vii vector<int>
 #define vll vector<long long>
 #define pii pair<int, int>
 #define pll pair<long,long>
 #define FAST_IO ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
 #define minheap priority_queue<long long, vector<long long>, greater<long long>>
 #define maxheap priority_queue<long long, vector<long long>>
const int MAX = 1e6;
const ll MOD = 1e9+7;

 void solve()
 {  
      ll n;cin>>n;
   if(n%2==0)
   {
    for(ll i=1;i<n;i+=2){
        cout<<i+1<<" "<<i<<" ";
    }
    cout<<endl;
   }
   else{
    vector<ll>v;
    for(ll i=1;i<n;i+=2){
        v.pb(i+1);
        v.pb(i);
    }

    
    ll c=v.back();
    v.pop_back();
    v.pb(n);
    v.pb(c);
    for(auto x:v){
        cout<<x<<" ";
    }
    nl;
   }
 }

int main()
{
    ios::sync_with_stdio(0); cin.tie(0);  
    
    ll t;          
    cin>>t;
    while(t--)
    {
      solve();
    }    
    
    
}