#include <cstdio>
#include <algorithm>

using namespace std;

int h[26];
char s[11];

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