/*
        SUPTO
        UNIVERSITY OF DHAKA
*/
#include <bits/stdc++.h>
using namespace std;
#define D(x) cerr<<#x " = "<<(x)<<endl
#define pb push_back
#define ff first
#define ss second
#define mem(a) memset(a,0,sizeof(a))
#define _set(a) memset(a,-1,sizeof(a))
typedef long long int ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
#define eps 1e-9
#define MAX 100000
#define MAXL 20
#define MAXE 100000
#define inf (1<<30)
//ll mod = 1000000000+7;
//int dx[] = {0,0,1,-1};
//int dy[] = {1,-1,0,0};
//int dx[] = {-1,-1,-1,0,0,1,1,1};
//int dy[] = {-1,0,1,-1,1,-1,0,1};
int h[30];
char ar[15];
int main()
{
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    int ncase, tcase = 1, i, mx = 0;
    for(i = 0; i < 26; i++) scanf("%d", &h[i]);
    scanf("%s", ar);
    int len = strlen(ar);
    for(i = 0; i < len; i++)
    {
        mx = max(mx, h[ar[i]-97]);
    }
    printf("%d\n", mx*len);
    return 0;
}