n = int(input())
s = input()
a = list(map(int, input().split()))

for i in range(n):
  if s[i] == 'B':
    a[i] = - a[i]

s = [0 for _ in range(n + 1)]
for i in range(n):
  s[i + 1] = s[i] + a[i]

ub = s[0]
lb = s[0]
ans = - 1 << 60
for i in range(1, n + 1):
  ans = max(ans, s[i] - lb, abs(s[i] - ub))
  ub = max(ub, s[i])
  lb = min(lb, s[i])

print(ans)