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

ans = S.count("-")
cnt1 = 0
cnt2 = S.count("+")
for i in range(N):
    if S[i] == "+":
        cnt2 -= 1
    if S[i] in ["0", "+"]:
        ans = max(ans, cnt1+cnt2+1)
    if S[i] == "-":
        cnt1 += 1

print(ans)