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 i in range(n+1)]
for i in range(n):
    s[i+1]=s[i]+a[i]
inf = 10**9
ma = [-inf for i in range(n+1)]
mi = [inf for i in range(n+1)]
for i in range(n):
    ma[-i-2]=max(ma[-i-1],s[-i-1])
    mi[-i-2]=min(mi[-i-1],s[-i-1])
ans1 = -inf
ans2 = inf
for i in range(n):
    ans1 = max(ans1,ma[i]-s[i])
    ans2 = min(ans2,mi[i]-s[i])

print(max(abs(ans1),abs(ans2)))