#include<bits/stdc++.h> using namespace std; using ll = long long; void solve() { int n; cin>>n; if(n==1) cout<<"1"<<endl; else if(n%2!=0) cout<<"-1"<<endl; else { for(int i=1; i<=n; i+=2) { cout<<i+1<<" "<<i<<" "; } cout<<endl; } } int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int TC = 1; cin >> TC; cin.ignore(); while (TC--) solve(); }