#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define sci(fd) scanf("%d",&fd)
#define scll(fd) scanf("%lld",&fd)
#define pb push_back
#define mp make_pair
#define MOD 1000000007
#define PI 3.1415926535897932
#define pii pair < int,int > 
#define fi first
#define se second
const ll infi=1000000000000000009;
int he[30];
char str[105];
int main()
{
    int i,j;
    for(i=0;i<26;i++)
    sci(he[i]);
	scanf("%s",str);
	int n=strlen(str);
	int a=0;
	for(i=0;i<n;i++)
	{
		a=max(a,he[str[i]-97]);
	}
	printf("%d\n",a*n);
    return 0;
}