#[macro_export]
macro_rules! setup {
    { mut $input:ident: SplitWhitespace $(,)? } => {
        use std::io::Read;
        let mut buf = String::new();
        std::io::stdin().read_to_string(&mut buf).ok();
        let mut $input = buf.split_whitespace();
    };
}

#[macro_export]
macro_rules! parse_next {
    ($str_iter:expr) => {
        $str_iter.next().unwrap().parse().ok().unwrap()
    };
}

fn main() {
    setup! { mut input: SplitWhitespace };

    let n: usize = parse_next!(input);
    let s: String = parse_next!(input);
    let mut a: Vec<i64> = (0..n).map(|_| parse_next!(input)).collect();

    s.chars().enumerate().for_each(|(i, c)| match c {
        'R' => {
            a[i] = a[i];
        }
        'B' => {
            a[i] = -a[i];
        }
        _ => unreachable!(),
    });

    let mut b = vec![0];
    for i in 0..n {
        b.push(b[i] + a[i]);
    }

    let ans = (|| {
        let min = *b.iter().min().unwrap();
        let max = *b.iter().max().unwrap();
        max - min
    })();

    println!("{}", ans);
}