import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        char[] colors = sc.next().toCharArray();
        long min = 0;
        long max = 0;
        long value = 0;
        long ans = 0;
        for (int i = 0; i < n; i++) {
            int x = sc.nextInt();
            if (colors[i] == 'B') {
                x *= -1;
            }
            value += x;
            ans = Math.max(ans, value - min);
            ans = Math.max(ans, max - value);
            min = Math.min(min, value);
            max = Math.max(max, value);
        } 
        System.out.println(ans);
    }
}