#include <bits/stdc++.h>
using namespace std;

#define MAX 100002

int a[MAX];
char s[MAX];

int main() {
	int i, n, len, max = -1;
	for (i=0; i<26; i++) {
	    scanf("%d", &a[i]);
	}
	scanf("%s", s);
	len = strlen(s);
	for (i=0; i<len; i++) {
	    if (max < a[s[i]-'a']) max = a[s[i]-'a'];
	}
	printf("%d", (len*max));
	return 0;
}