package main

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

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

	var s string
	if _, err := fmt.Fscan(in, &s); err != nil {
		return
	}
	var k int
	fmt.Fscan(in, &k)
	w := make([]int64, 26)
	var mx int64
	for i := 0; i < 26; i++ {
		fmt.Fscan(in, &w[i])
		if w[i] > mx {
			mx = w[i]
		}
	}

	var ans int64
	for i := 0; i < len(s); i++ {
		idx := int(s[i] - 'a')
		ans += int64(i+1) * w[idx]
	}
	n := len(s)
	for j := 1; j <= k; j++ {
		ans += int64(n+j) * mx
	}
	fmt.Fprintln(out, ans)
}