#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
#define inf (0x3f3f3f3f)
typedef long long int LL;

#include <iostream>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <string>

const int maxn=  1e5+20;
char str[maxn];
int h[maxn];
void work ()
{
    for (int i=1;i<=26;++i)
    {
        int val;
        scanf("%d",&val);
        h[i+'a'-1]=val;
    }
    int ans=0;
    scanf("%s",str+1);
    int lenstr = strlen(str+1);
    int t=-inf;
    for (int i=1;i<=lenstr;++i)
    {
        t=max(t,h[str[i]]);
    }
    printf ("%d\n",t*lenstr);
    return ;
}
int main()
{
#ifdef local
    freopen("data.txt","r",stdin);
#endif
    work();
    return 0;
}