/*
 *   Copyright (c) 2025 Emon Thakur
 *   All rights reserved.
 */
#include<bits/stdc++.h>
using namespace std;
void solve()
{
    int n; cin >> n;
    vector<int> ans(n+1);
    for(int i=1;i<=n;i++) ans[i]=i;
    if(n%2)
    {
        for(int i=1;i<=n-3;i+=2) swap(ans[i],ans[i+1]);
        swap(ans[n],ans[n-1]);
        swap(ans[n],ans[n-2]);
    }
    else
    {
        for(int i=1;i<=n;i+=2) swap(ans[i],ans[i+1]);
    }
    for(int i=1;i<=n;i++) cout<<ans[i]<<' '; cout<<'\n';
}
int main()
{
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int t; cin >> t; while(t--) solve();
}