import sys
input = sys.stdin.readline

N=int(input())
S=input().strip()
A=list(map(int,input().split()))

for i in range(N):
    if S[i]=="B":
        A[i]=-A[i]

from itertools import accumulate

S=[0]+list(accumulate(A))


MAX=[]
MIN=[]
ma=0
mi=0
for i in range(N+1):
    ma=max(ma,S[i])
    mi=min(mi,S[i])

    MAX.append(ma)
    MIN.append(mi)

ANS=0

for i in range(N+1):
    ANS=max(ANS,abs(S[i]-MAX[i]))
    ANS=max(ANS,abs(S[i]-MIN[i]))

print(ANS)