# import sys
# input = sys.stdin.readline
def mp():return map(int,input().split())
def lmp():return list(map(int,input().split()))
import math
import bisect
from copy import deepcopy as dc
from itertools import accumulate
from collections import Counter, defaultdict, deque
def ceil(U,V):return (U+V-1)//V
def modf1(N,MOD):return (N-1)%MOD+1
inf = int(1e30)
mod = 998244353

n =int(input())
s = input()
a = lmp()
for i in range(n):
    if s[i] == "B":a[i]*=-1
a = [0] + list(accumulate(a))
mx = list(accumulate(a, func=max))
mn = list(accumulate(a, func=min))
print(mx[-1]-mn[-1])