#include <bits/stdc++.h>

using namespace std;

const int N = 20;
char s[N];
int a[26];

int main()
{
  for (int i = 0; i < 26; ++i) {
    scanf("%d", a + i);
  }
  scanf("%s", s);
  
  int n = strlen(s);
  int mx = 0;
  for (int i = 0; i < n; ++i) {
    mx = max(a[s[i] - 'a'], mx);
  }
  
  printf("%d\n", mx * n);
  return(0);
}