#include <bits/stdc++.h>
using namespace std;

int main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        if (n % 2 == 0)
        {
            for (int i = 1; i < n; i += 2)
            {
                cout << i + 1 << " " << i;
                if (i < n - 1)
                    cout << " ";
                else
                    cout << endl;
            }
        }
        else
        {
            for (int i = 1; i < n - 2; i += 2)
            {
                cout << i + 1 << " " << i << " ";
            }
            cout << n - 1 << " " << n << " " << n - 2 << endl;
        }
    }
}