#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <set>
#include <map>
#include <string>
#include <algorithm>

using namespace std;

int main() {
  int h[26];
  for (int i = 0; i < 26;i++) {
    scanf("%d", &h[i]);
  }
  char word[30];
  scanf("%s", word);
  int w = 0, hh = 0;
  for (int i = 0; word[i]; i++) {
    w++;
    hh = max(hh, h[word[i] - 'a']);
  }
  printf("%d\n", w*hh);
  return 0;
}