package main

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

func reverse(s string) string {
	b := []byte(s)
	for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
		b[i], b[j] = b[j], b[i]
	}
	return string(b)
}

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

	var t int
	fmt.Fscan(in, &t)
	for ; t > 0; t-- {
		var n int
		fmt.Fscan(in, &n)
		long := make([]string, 0, 2)
		for i := 0; i < 2*n-2; i++ {
			var s string
			fmt.Fscan(in, &s)
			if len(s) == n-1 {
				long = append(long, s)
			}
		}
		if reverse(long[0]) == long[1] {
			fmt.Fprintln(out, "YES")
		} else {
			fmt.Fprintln(out, "NO")
		}
	}
}