#include <stdio.h>
#include <string.h>

#define max(a, b) (a > b ? a : b)

int main( void ) {
	int h[26];
	for( int i = 0; i < 26; i++ ) {
		scanf("%i", &h[i]);
	}
	
	char word[100];
	scanf("%s", word);
	
	int tallest = 0;
	int n = strlen(word);
	for( int i = 0; i < n; i++ ) {
		tallest = max(tallest, h[word[i]-'a']);
	}
	
	printf("%i\n", n * tallest);
	
	return 0;
}