/* GREEN UNIVERSITY OF BANGLADESH
    Md DinIslam, Batch-221 (CSE)
*/
#include <bits/stdc++.h>
using namespace std;

// Debug..
#ifdef LOCAL
#include "debug.h"
#else
#define dg(x...)
#endif

#define ll long long
#define all(x) x.begin(), x.end()
#define pb push_back
#define sz(x) int(x.size())
#define arr array

void Din() {
    int n;
    cin >> n;

    vector<int> v(n + 1);
    iota(all(v), 0);
    
    for (int i = 2; i <= n; i += 2) {
        swap(v[i], v[i - 1]);
    }
    
    // dg(v);
    
    if (n & 1) {
        swap(v[n], v[n - 1]);
    }

    for (int i = 1; i <= n; ++i) {
        cout << v[i] << " \n"[i == n];
    }
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    int t = 1;
    cin >> t;
    for (int i = 1; i <= t; ++i) {
        // cout << "Case " << i << ": ";
        Din();
    }
    return 0;
}