#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,ll>
#define ff first
#define ss second
#define mp make_pair
#define pb push_back
#define N 100005
#define ll long long 
#define MOD 1000000007
int h[N];
int main()
{
  int i,m=-1,ans,l;
    char s[N];
  for(i=0;i<26;i++)
  {
     scanf("%d",&h[i]);
  }
  scanf("%s",s);
  l=strlen(s);
  for(i=0;i<l;i++)
  {
      m=max(m,h[s[i]-'a']);
  }
  ans=m*l;
  printf("%d\n",ans);
  return 0;
}