package 动态规划;
import java.util.Scanner;

 
public class hdu_1243 {
    static int []value;
    static String str1,str2;
    public static void main(String[] args) {
        Scanner sc =new Scanner (System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            String str = sc.next();
            char [] a = str.toCharArray();
            value = new int[100];
            for(int i=0;i<n;i++){
                int num = sc.nextInt();
                value[a[i]-‘a‘] = num;
            }
            str1 = sc.next();
            str2 = sc.next();
            LCS(str1,str2);
        }
        
    }
    

    private static void LCS(String str, String str1) {
        char [] x =str.toCharArray();
        char [] y = str1.toCharArray();
        int[][] dp = new int [x.length+1][y.length+1];
        for(int i=1;i<x.length+1;i++){
            for(int j=1;j<y.length+1;j++){
                if(x[i-1]==y[j-1]){
                    dp[i][j]=dp[i-1][j-1]+value[str.charAt(i-1)-‘a‘];
                }else if(dp[i-1][j]>dp[i][j-1]){
                    dp[i][j]=dp[i-1][j];
                }else {
                    dp[i][j]=dp[i][j-1];
                }
            }
        }
        System.out.println(dp[x.length][y.length]);
    }
}