N = int(input())
s = list(input())

cnt = 0
for i in range(N):
    if s[i] == "+":
        cnt += 1

ans = cnt 
minuscnt = 0

for i in range(N):
    if s[i] == "-":
        minuscnt += 1
        ans = max(ans, cnt + minuscnt)
    elif s[i] == "0":
        ans = max(ans, cnt + minuscnt + 1)
    else:
        cnt -= 1
        ans = max(ans, cnt + minuscnt)

print(ans)