def Kadane(a):
   v = -1<<60 # i を右端とする区間和のmax
   m = -1<<60 # max(v0,...,vi)
   for ai in a:
       v = max(v+ai,ai)
       m = max(m,v)
   return m

n = int(input())
s = input()
*a, = map(int,input().split())
for i in range(n):
    if s[i]=="B": a[i] = -a[i]
x = abs(Kadane(a))
for i in range(n):
    a[i] = -a[i]
y = abs(Kadane(a))
print(max(x,y))