n = int(input())
s = input() + "?"
a = [0]
b = [0]

for i in range(n):
    a.append(a[-1])
    b.append(b[-1])
    if s[i] == "-":
        a[-1] += 1
    if s[i] == "+":
        b[-1] += 1

ans = 0
for i in range(n + 1):
    ans = max(ans, a[i] + b[-1] - b[i] + int(s[i] == "0"))
print(ans)