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

p = [0] * (N + 1)
m = [0] * (N + 1)

for i in range(N):
    p[i + 1] += p[i] + (S[i] == '+')
    m[i + 1] += m[i] + (S[i] == '-')

ans = 1
for i in range(N):
    if S[i] == '-':
        ans = max(ans, m[i + 1] + p[N] - p[i + 1])
    elif S[i] == '+':
        ans = max(ans, m[i] + p[N] - p[i])
    else:
        ans = max(ans, m[i] + p[N] - p[i + 1] + 1)
print(ans)