mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    N = int(input())
    S = input().rstrip('\n')
    A = list(map(int, input().split()))

    for i, s in enumerate(S):
        if s == "B":
            A[i] *= -1

    cs = [0] * (N+1)
    for i in range(N):
        cs[i+1] = cs[i] + A[i]
    ans = 0
    ma = mi = 0
    for i in range(1, N+1):
        ans = max(ans, abs(cs[i] - mi), abs(cs[i] - ma))
        mi = min(mi, cs[i])
        ma = max(ma, cs[i])
    print(ans)


if __name__ == '__main__':
    main()