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

 #include <bits/stdc++.h>
 #include<ext/pb_ds/assoc_container.hpp>
 #include<ext/pb_ds/tree_policy.hpp>
 using namespace std;
 using namespace __gnu_pbds;
 
 #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>>
 typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds; // find_by_order, order_of_key
 template <typename... T>
 void read(T&... args){((cin>>args), ...);}
 template <typename... T>
 void write(T... args){((cout<<args<<" "), ...);}
 
 const int INF = 1e9;
 const ll MOD = 1e9 + 7;
 const double EPS = 1e-9;
 const int MAX = 10000001;
 
 #ifdef ONLINE_JUDGE
 #define debug(...) 42
 #else
 #include "algo/debug.h"
 #endif
 
 void solve(int tc)
 {  
   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()
 {
     FAST_IO;
     #ifndef ONLINE_JUDGE
     freopen("Error.txt","w",stderr);
     #endif
     int t = 1;
     int tt=1;  
     cin >> t;
     while (t--)
     {
         solve(tt++);
     }
     return 0;
 }