from itertools import accumulate
N = int(input())
S = str(input())
A = list(map(int,input().split()))
for i in range(N):
    if S[i] == 'B':
        A[i] = -A[i]
AC = list(accumulate(A))

mi,ma = min(AC),max(AC)
mii,maa = mi,ma
for i in range(N):
    mi = min(mi,mii-AC[i])
    ma = max(ma,maa-AC[i])
ans = max(abs(mi),ma)
print(ans)