package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	reader := bufio.NewReader(os.Stdin)
	writer := bufio.NewWriter(os.Stdout)
	defer writer.Flush()

	var t int
	if _, err := fmt.Fscan(reader, &t); err != nil {
		return
	}

	for tc := 0; tc < t; tc++ {
		var n int
		fmt.Fscan(reader, &n)

		if n == 1 {
			fmt.Fprintln(writer, 1)
		} else if n%2 != 0 {
			fmt.Fprintln(writer, -1)
		} else {
			for i := n; i >= 1; i -= 2 {
				if i < n {
					fmt.Fprint(writer, " ")
				}
				fmt.Fprintf(writer, "%d %d", i-1, i)
			}
			fmt.Fprintln(writer)
		}
	}
}