N = int(input())
S = input()
plus = [0 for _ in range(N + 1)]
minus = [0 for _ in range(N + 1)]
for i in range(N - 1, -1, -1):
    plus[i] = plus[i + 1]
    if S[i] == '+':
        plus[i] += 1
for i in range(N):
    minus[i + 1] = minus[i]
    if S[i] == '-':
        minus[i + 1] += 1
ans = 0
for i in range(N):
    ans = max(ans, minus[i] + plus[i])
for i in range(N):
    if S[i] == '0':
        ans = max(ans, minus[i] + plus[i + 1] + 1)
print(ans)