#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int > pii;
typedef pair<int,pii > piii;
typedef vector<int>     VI;
//input
#define sc1(x) scanf("%d",&x);
#define sc2(x,y) scanf("%d%d",&x,&y);
#define sc3(x,y,z) scanf("%d%d%d",&x,&y,&z);

/*
#define sc1(x) scanf("%lld",&x);
#define sc2(x,y) scanf("%lld%lld",&x,&y);
#define sc3(x,y,z) scanf("%lld%lld%lld",&x,&y,&z);
*/

#define pb push_back
#define mp make_pair
#define ini(x,val) memset(x,val,sizeof(x));

#define fs first
#define sc second

//some constants
#define MOD 1000000007
#define inf 999999999
#define linf 99999999999999999ll	//long long inf
#define PI 3.1415926535897932384626
const double eps=0.000000000000001 ;

#define gcd __gcd
#define tr(container, it)  for(typeof(container.begin()) it = container.begin(); it != container.end(); it++) 
#define PrintCont(cont) {cout<<("\n----------------\n");\
for(typeof(cont.begin()) it = cont.begin();it!=cont.end();++it) cout<<*it<<" ";cout<<("\n----------------\n");}
#define all(v) v.begin(),v.end()
#define fast_io ios_base::sync_with_stdio(false);cin.tie(NULL)

#define debug(x) cout<<#x<<" :: "<<x<<"\n";
#define debug2(x,y) cout<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\n";
#define debug3(x,y,z) cout<<#x<<" :: "<<x<<"\t"<<#y<<" :: "<<y<<"\t"<<#z<<" :: "<<z<<"\n";

#define LIM 100005
int h[30];
int main()
{
	int i,j;
	for(i=0;i<26;++i)
	{
		sc1(h[i]);
	}
	char s[100];
	scanf("%s",s);
	int mx = 0,c=0;
	for(i=0;s[i];++i)
	{
		mx = max(mx,h[s[i]-'a']);
		c++;
	}
	printf("%d\n",c*mx);

	return 0;
}