/****************************************************************
 *    sonu kumar
 *    MNNIT allahabad
 *    computer science and engineering
 ****************************************************************/
 #include<bits/stdc++.h>
 #define ll long long int 
 #define mod 1000000007
 #define INF 1000000007
 #define pb(i) push_back(i) 
 #define mp(i,j) make_pair(i,j)
 #define pi    pair<int,int>
 #define pii   pair<int,pair<int,int> >
 #define scs(str) scanf("%s",str)
 #define sci(i) scanf("%d",&i)
 #define scl(i) scanf("%lld",&i)
 #define sci2(a,b) scanf("%d%d",&a,&b)
 #define scl2(a,b) scanf("%lld%lld",&a,&b)
 #define sci3(x,y,z) scanf("%d%d%d",&x,&y,&z)
 #define scl3(x,y,z) scanf("%lld%lld%lld",&x,&y,&z)
 #define chk(a) cout << endl << #a << " : " << a << endl
 #define chk2(a,b) cout << endl << #a << " : " << a << "\t" << #b << " : " << b << endl
 using namespace std;
 int main()
 {
     int h[26];
     for(int i=0;i<26;i++)
         cin>>h[i];
     cin.ignore();
     char str[20];
     cin>>str;
     int l=strlen(str);
     int ans=0;
     for(int i=0;i<l;i++)
         ans=max(ans,h[str[i]-'a']);
     cout<<ans*l;
     return 0;
 }