#include<bits/stdc++.h>

using i64 = long long int;
using u64 = unsigned long;
using d96 = long double;

void solve(){
    int n;
    std::cin>>n;
    std::vector<int> v(n);
    for(int i = 0;i<n;i++){
        v[i] = i + 1;
    }
    for(int i = 1;i<n;i+=2){
        std::swap(v[i], v[i-1]);
    }
    if(n%2 == 1){
        std::swap(v[n-1], v[n-2]);
    }
    for(int i = 0;i<n;i++){
        std::cout<<v[i]<<" \n"[i==n-1];
    }
}

int main()
{
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int t = 1;
    std::cin>>t;
    while(t--){
        solve();
    }

    return 0;
}