#ifndef LOCAL
#include <bits/stdc++.h>
#define debug(...)
#endif

using namespace std;
#define int long long
#define cinv(v) for (auto &it:v) cin>>it;
#define coutv(v) for (auto &it:v) cout<< it<<' '; cout<<'\n';

void shelby() {
    int n;
    cin >> n;
    vector<int> v(n);
    iota(v.begin(), v.end(), 1);
    for (int i = 1; i < n; i += 2) swap(v[i], v[i - 1]);
    if (n % 2) swap(v[n - 1], v[n - 2]);
    coutv(v)
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
    cin >> t;
    for (int _ = 1; _ <= t; ++_) {
        // cout << "Case " << _ << ": ";
        shelby();
    }
}