def main():
  import sys
  readline = sys.stdin.readline
  def error(*args, end='\n'):
    print(*args, end=end, file=sys.stderr)
  n = int(readline())
  s = readline()[:-1]
  A = list(map(int, readline().split()))
  now = 0
  ans = 0
  maxv, minv = 0, 0
  for i in range(n):
    if s[i] == 'B':
      A[i] *= -1
  error(A)
  for i in range(n):
    now += A[i]
    ans = max(ans, abs(now - minv))
    ans = max(ans, abs(now - maxv))
    error(ans, now, minv, maxv)
    minv = min(minv, now)
    maxv = max(maxv, now)
  print(ans)
  
if __name__ == "__main__":
  main()