def _min(a,b);a < b ? a : b; end
N = gets.to_i
S = gets.chomp.chars
A = gets.split.map(&:to_i)
dp = Array.new(N + 1, Float::INFINITY)
ndp = Array.new(N + 1, Float::INFINITY)
dp[0] = 0
S.zip(A) do |s,a|
  (0 .. N).each do |d|
    if s == ?(
      ndp[d + 1] = _min(dp[d], ndp[d + 1]) if d + 1 <= N
      ndp[d - 1] = _min(dp[d] + a, ndp[d - 1]) if d - 1 >= 0      
    else
      ndp[d + 1] = _min(dp[d] + a, ndp[d + 1]) if d + 1 <= N
      ndp[d - 1] = _min(dp[d], ndp[d - 1]) if d - 1 >= 0
    end
  end
  ndp, dp = dp, ndp
  ndp.fill(Float::INFINITY)
end
puts dp[0]