#include <bits/stdc++.h>
#define ll long long int
#define endl '\n'
#define pb push_back
#define pf push_front
#define mp make_pair
#define eb emplace_back
#define popb pop_back
#define popf pop_front
#define ff first
#define ss second
#define here cout<<"HERE !!!"<<endl;
#define sz(v) (ll)v.size()
#define vi vector<ll>
#define print(v) for (auto it : v) cout << it << " "; cout << endl;
#define all(v) v.begin(), v.end()
#define read(v) for(auto &it:v) cin>>it;
#define Faster ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set tree<ll, null_type,less_equal<ll>, rb_tree_tag,tree_order_statistics_node_update>
using namespace  __gnu_pbds;
using namespace std;
const long double pi = acos(-1.0l);
const ll inf = 1e18;
const int mod = 998244353, mx = 2e5 + 5;
//rotate(v.begin(), v.begin() + d, v.end());
//order_of_key(k): number of element less than k
//find_by_order(k): k-th element in set start from 0

void ravana(ll idx)
{
    ll n;   cin >> n;
    vi v(n);
    iota(all(v), 1);
    for (ll i = 0; i + 1 < n; i += 2)
    {
        swap(v[i], v[i + 1]);
    }
    if (n % 2)
        swap(v[n - 1], v[n - 2]);
    print(v);
}
signed main()
{
    auto begin = std::chrono::high_resolution_clock::now();
    Faster;
    ll t = 1;
    cin >> t;
    for (ll i = 1; i <= t; ++i)
    {
        ravana(i);
    }
    auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
    cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n";
    return 0;
}