#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define TRACE(x) cerr << #x << " = " << x << endl
#define _ << " _ " <<

#define x first
#define y second
#define pb push_back

using namespace std;

typedef long long ll;



int main(void) {
  ios_base::sync_with_stdio(false);
  int v[256];
  REP(i, 26) cin >> v['a' + i];
  string s;
  cin >> s;
  int mx = 0;
  for (auto c : s) mx = max(mx, v[c]);
  int ans = mx * s.size();
  cout << ans << endl;
  return 0;
}