object Solution {

    def main(args: Array[String]) {
        val sc = new java.util.Scanner (System.in);
        val n = 26;
        var h = new Array[Int](n);
        for(h_i <- 0 to n-1) {
           h(h_i) = sc.nextInt();
        }
        var word = sc.next();
        println(word.size*word.toCharArray.map(c=>h(c.toInt-97)).toSeq.max);
    }
}