N = gets.to_i
S = gets.chomp
a = gets.split.map(&:to_i)
S.each_char.with_index do |c, i|
    a[i] *= -1 if c == ?B
end

def find_max_continuous_subsequence(a)
    cumsum = [0]
    a.each do |x|
        cumsum << cumsum[-1] + x
    end
    cummax = [0]
    cumsum.reverse_each do |x|
        cummax.unshift [cummax[0], x].max
    end
    r = a.size
    (0 ... a.size).map { |l| cummax[l + 1] - cumsum[l] }.max
end

ans = find_max_continuous_subsequence(a)
a.map! { |x| -x }
ans = [ans, find_max_continuous_subsequence(a)].max
puts ans