#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <stack>
#include <map>
#include <set>
#include <deque>
#include <cstring>
#include <functional>
#include <climits>
#include <list>
#include <ctime>
#include <complex>
#include <ext/rope>

#define F1(x,y,z) for(int x=y;x<z;x++)
#define F2(x,y,z) for(int x=y;x<=z;x++)
#define F3(x,y,z) for(int x=y;x>z;x--)
#define F4(x,y,z) for(int x=y;x>=z;x--)
#define mp make_pair
#define pb push_back
#define LL long long
#define co complex<double>
#define fi first
#define se second

#define MAX 100005
#define AMAX 1500
#define MOD 1000000007

#define f(c,d) ((1<<(c))*(d))

using namespace std;
using namespace __gnu_cxx;

int x[30],i,ans;
char y[20];

int main(){
	F1(a,0,26)scanf("%d",x+a);
	scanf("%s",y);
	while(y[i])ans=max(ans,x[y[i++]-'a']);
	printf("%d\n",ans*i);
	#ifdef LOCAL_PROJECT
	system("pause");
	#endif
	return 0;
}