package main

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

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

	var t int
	fmt.Fscan(reader, &t)

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

		k := 1
		if n > 1 && s[0] > s[1] {
			for k < n && s[k] <= s[k-1] {
				k++
			}
		}

		res := make([]byte, 2*k)
		for j := 0; j < k; j++ {
			res[j] = s[j]
			res[2*k-1-j] = s[j]
		}
		fmt.Fprintln(writer, string(res))
	}
}