//Lower bound: first element that is greater-or-equal.
//Upper bound: first element that is strictly greater.
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <string.h>
#include <algorithm>
#include <math.h>
#include <vector>
#include <queue>
#include <set>
#include <stack>
#include <map>
#define INF_MAX 2147483647
#define INF_MIN -2147483647
#define INF_LL 9223372036854775807LL
#define INF 2000000000
#define PI acos(-1.0)
#define inf INT_MAX
#define llu unsigned long long int
#define all(v) v.begin(),v.end()
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define si(n) scanf("%d",&n)
#define slli(n) scanf("%lld",&n);
#define ss(n) scanf("%s",n);
//the primes for string hashing
//#define M 1000000009
//#define p 999983
//#define pinverse 943912055
//hash --> A[i]=sum(j=1..i)(a[i]*p^i)%M
using namespace std;
typedef long long int LL;
/*
long long int mmax(long long int a , long long int b){
	if(a>b)
		return a;
	return b;
}
typedef struct node{
	int a;
}node;
vector<int > primes;
int is_prime[1000010];
void seive(){
for(int i=0;i<=1000005;i++)
	is_prime[i] = 1;
is_prime[1] = 0;
is_prime[0] = 0;
for(long long int j=2;j<=1000000;j++){
	if(is_prime[j]==1){
		primes.push_back(j);
		for(long long int k=(j*j);k<=1000000;k+=j)
			is_prime[k] = 0;
	}
}
}
//int prime(long long int x){if(x==1)return 0;if(x<=3)return 1;if(x%6==1||x%6==5){long long int y=sqrt(x),i;for(i=2;i<=y;i++)if(x%i==0)return 0;return 1;} return 0;}
//long long int fastpow(long long int a, long long int b,long long int m){long long int r = 1;while (b > 0){if (b % 2 == 1)r = (r * a) % m;b = b >> 1;a = (a * a) % m;}return r;}
//long long int gcd(long long int m, long long int n){if(n == 0) return m;return gcd(n, m % n);} 
int compare(const void *a , const void *b){
	struct node *x,*y;
	x = (struct node *)a;
	y = (struct node *)b;
	return 1;
}
*/
int h[30] , len;
string ip;
int main()
{
for(int i=1;i<=26;i++)
	si(h[i]);
cin >> ip;
int block_height = 0;
len = ip.length();
for(int i=0;i<len;i++)
{
	block_height = max(block_height , h[ip[i] - 'a' + 1]);
}

int ans = block_height * len;
printf("%d\n", ans);

return 0;
}