#include <bits/stdc++.h>     //   All praise is due to Allah alone, and peace and blessings be
using namespace std;         //         upon him, after whom there is no other Prophet.

int32_t main() {
    cin.tie(0)->sync_with_stdio(false);

    function<void()> Test_Case = [&]() {
        int n; cin >> n;
        int ar[n];
        iota(ar, ar + n, 1);
        for(int i = 0; i < n - 1; i += 2) {
            swap(ar[i], ar[i + 1]);
        }
        if(n & 1) swap(ar[n - 2], ar[n - 1]);
        for(int i : ar) cout << i << ' '; cout << '\n';
    };

    int32_t Case = 1;    cin >> Case;
    for (int T = 1; T <= Case; T++) {
        Test_Case();
    }
    return 0;
}