#include<bits/stdc++.h>
using namespace std;
set<long long> s;
set<long long>::iterator it;
map<long long,long long> mp;
pair<long long,long long> p[1000],p1[1000];
int main()
{
    long long i,j,f=0,k,l,m,n,t,a[300001],x,c=1,y,z=1,type,q,b[300001],ans=1000000000000;
    double s2=1000000000,sum;
    string s;
    for(i=0;i<26;i++)
    {
      cin>>mp[i+97];
    }
    cin>>s;
    l=s.length();
    for(i=0;i<l;i++)
    {
      f=max(mp[s[i]],f);
    }
    cout<<l*f<<endl;
    return 0;
}