n = int(input())
s = input()
a = list(map(int, input().split()))
l = [0]
for i in range(n):
    ri = a[i] if s[i] == "R" else 0
    bi = a[i] if s[i] == "B" else 0
    l.append(l[-1] + (ri - bi))
print(max(l) - min(l))