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

		var a, b string
		fmt.Fscan(reader, &a, &b)

		i := 0
		for j := 0; j < m && i < n; j++ {
			if a[i] == b[j] {
				i++
			}
		}
		fmt.Fprintln(writer, i)
	}
}