#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
  int letters[26];
  for(int i = 0; i < 26; ++i) cin >> letters[i];
  char *line = (char*)malloc(11);
  std::cin >> line;
  int max = 0, count;
  while(*line != '\0') {
    if(letters[*line - 'a'] > max) max = letters[*line - 'a'];
    ++line;
    ++count;
  }
  std::cout << max * count;
    return 0;
}