package main

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

func main() {
	r := bufio.NewReader(os.Stdin)
	var n, k int
	fmt.Fscan(r, &n, &k)
	
	var s string
	fmt.Fscan(r, &s)
	
	a := make([]bool, 256)
	for i := 0; i < k; i++ {
		var c string
		fmt.Fscan(r, &c)
		if len(c) > 0 {
			a[c[0]] = true
		}
	}
	
	var ans, c int64
	for i := 0; i < n; i++ {
		if a[s[i]] {
			c++
		} else {
			ans += c * (c + 1) / 2
			c = 0
		}
	}
	ans += c * (c + 1) / 2
	
	fmt.Println(ans)
}