N = int(input())
S = input()

xs = [0] * (N+1)
for i in reversed(range(N)):
    if S[i] == '+':
        xs[i] += 1

    xs[i] += xs[i+1]


ans = xs[0]
neg = 0
for i in range(N):
    if S[i] == '-':
        neg += 1
        ans = max(ans, neg+xs[i+1])

    if S[i] == '0':
        ans = max(ans, neg + xs[i+1] + 1)

print(ans)