#include <bits/stdc++.h>

using namespace std;

int a[ 2005 ];

int main()
{
	for( int i = 0; i < 26; i++ )
	{
		scanf( "%d\n", &a[ i ] );
	}

	string s;
	cin >> s;

	int maxx = 0;

	for( char c : s )
	{
		maxx = max( maxx, a[ c - 'a' ] );
	}

	int ans = s.size() * maxx;

	cout << ans << endl;

	return 0;
}