#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int n;
    cin >> n;

    while (n--) {
        int k;
        cin>>k;

        if(k%2 ==0){
            for(int i=1; i<=k; i+=2){
                cout<<i+1 <<" " <<i <<" ";
            }
        }
        else if(k%2!=0){
            for(int i=1; i<=k-3; i+=2){
                cout<<i+1 <<" " <<i <<" ";
            }
            cout<<k-1 <<" " <<k <<" " <<k-2;
        }
        cout<<endl;
    }

    return 0;
}