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

l = [A[i] if S[i] == 'R' else -A[i] for i in range(N)]

Sum = [0] * (N+1)
for i in range(N):
    Sum[i+1] = Sum[i] + l[i]
M = max(Sum)
m = min(Sum)

print(abs(M-m))